Mayor Vaughn’s attire...

Yes they dressed like that.

Yes, men dressed like that in the 1970s... if they had no taste.

Costume is supposed to reveal character, and what the Mayor's tacky outfits show is a man with money to spend, no taste, and a desire to attract attention by any means at his disposable. His outfits are tacky and showy, not the sort of thing a cool guy would wear, more what a successful car salesman would think was sharp.