Why didn't anyone catch on to the boys' involvement?

With all the people on King's payroll including two men watching the motel and his other son, I'm surprised no one caught on to the boys and followed them to the island (yes, Neckbone's uncle did but he didn't count).

After the "We're selling fish" incident in the motel room, the boys aren't clever enough to continue going door to door selling fish but instead leave right away. The brother is watching them and the camera lingers on that a bit but nothing comes of it.

Ellis may have thought he was being sneaky, but he's just a kid and he goes straight to Juniper's door a number of times, yet no one thinks to follow him.

It didn't harm the movie for me or anything like that, but I thought the boys' carelessness was going to be part of the plot, leading the hired guns to the island.