This film was not shocking in any sense

In Europe, criminal law is very different to the UK (even though there are common/shared standards for certain parts due to the EU), I have explained the legal situation here in the next paragraph (BTW I strongly doubt that anyone is impressed by these kids, and if you look at other entries in this forum you'll find that there are plenty of upper middle class kids from "good households" who got into the same sh*t these kids got into - good parenting isn't the sole factor in raising a kid, other influences that are basically beyond the parents also play into the situation, such as friends - and believe me, unless you deny your kids any trust and put them under 24/7 surveillance like a control freak you won't be able to prevent these outside influences - especially not if the kid is raised by a single mother and the father has little say in their upbringing, which is a rampant problem in both Europe and particularly the UK from what I've heard/read).

Regarding criminal law in Europe (as said, very different than in the UK):
Youths under 14 are totally free of any liability (all the police can do when they catch them doing something wrong is to call their parents & tell them off, if the parents are not available or even in the country the kids are set free - I saw on TV that same applies in Germany, which is why Gypsies bring trained pickpocket kids into our countries who claim to be unaccompanied minors so the police can't do anything against them as long as they're under 14, even if they're arrested multiple times within a day for serious offences such as attempts of abusing credit cards.).
Between 14 and 17, first offences are ALWAYS striken from all records when the kid turns 18, except if multiple offences have been committed or if the crime was of sexual nature. Also, if people commit a 2nd crime while underage, the judge can decide to suspend prosecution indefinitely under the provision that no further offences are committed (which is basically the 2nd/last chance to prevent a police record, and it is often made use of by courts as giving someone a record isn't taken lightly and is considered kind of a last resort before locking them up). Courts basically try to avoid giving people records unless they refuse to learn from their mistakes, and usually prefer other means of teaching people a lesson as they know that preventing people from getting a good job will only increase their chance of re-offending.
Thus, people can also appeal to the president (through the ministry internal affairs) for a striking of their entire criminal record (even if this features multiple entries and/or offences committed as adults) if haven't reoffended for a certain amount of time (which is usually granted, but only once in a lifetime and only for crimes that didn't involve sex or excessive violence).
Custodial consequences are VERY hard to implement in (continental) European countries, and are usually only even considered if the kid has already been arrested multiple times for relatively serious offences and the parent admits that they see no way of getting them in line (many kids are raised by single mothers who simply have to work & can't afford babysitters, and society deems it unfair to punish them by taking their children away from them because they couldn't work and look after them at the same time).

I think you just got wrong what we meant by "wish they would get arrested" - what I meant is that I'd rather have my child try something stupid and be shown the consequences ONCE while they're underage, rather than have them make that same mistake at an age where being arrested leaves much less of an intimidating impression (as adults know their rights, can call lawyers, etc.) and has much more serious consequences (life-long record) if they are as stupid as to make any mistake after their 18th birthday (be it only days after that).

No one wants their children to commit serious crimes (let alone get a criminal record), and THEREFORE smart people would prefer to have their kids make mistakes as long as it doesn't affect their future rather than having them grow up in a care-free environment where the small mistakes they make don't have any serious consequences, leaving them with less of a grasp of the risk they are taking if they decide to break the law at a later point in life (people's brains aren't fully developed until they're about 26, so I'd rather my kid makes a mistake and learns from it while they're underage rather than to fear them making mistakes at an age where they don't get away with a slap on the wrist even if it is/remains their first and last offence.

Of course no one wants their children to become serious criminals or commit crimes, but given the increasing stupidity of todays system (where people need to step down from top jobs for having shoplifted a lolly in their childhood, whereas banksters who - in full knowledge of the potential consequences - cause serious damage to the taxpayer/economy are rewarded with bonuses), we'd just prefer the kids to make their mistakes while it doesn't affect their future careers rather than have them ruin their career after making a stupid mistake out of lack of awareness of the consequences they may face once they're 18. As mentioned before, many children (if not the majority) are raised by single mothers (and the father has little chance of having any meaningful influence), so good parenting is pretty much a luxury few kids are lucky enough to receive (and many parents are denied to provide). Given this situation, add in high schools that have people leaving without even being able to read/write properly (let alone teaching them morality/values, but instead they're increasingly having young boys put on medication for acting aggressively compared to girls, a trend that is coming to UK/Europe now from the US), a lack of morals taught/demonstrated by society as a whole (which is promoted in the media etc), and you might see why we're not as misguided as it may seem.

A law that makes a 40 year old man step down from a top job for having stolen a can of soda when he was A CHILD is stupid BTW (if he robbed an old lady, I could see the point, but let's stick to the given example), and having such laws only contributes towards pushing people into criminality. If I was denied a job I worked 30 years to earn because of some minor infringement I committed as a child - while pedophiles are protected by police (see Rotherham, Gary Glitter, allegedly PM Edward Heath) - I doubt I would continue to respect/abide by the law as strictly as I do now.