Question- Beer on tap in Summer time

A few things.

Skunking of a beer can happen in less than a minute in direct sunlight. It has happened to me.

I tried to get a British Summer Ale to skunk in direct sunlight in London. I drank slowly, and was smelling often trying to detect it. I could not pick it up. Do British Brewers use hydrogenated Hop extract for bittering? I have always seen pellets in the ones I have toured.

Skunking is a reaction between the Isohumulone (an acid, not one of the hop oils), light, and riboflavin. The riboflavin is a byproduct of fermentation and the malt.
https://beersensoryscience.wordpress.com/2011/03/17/lightstruck/

When reading the OP, I thought dirty lines and faucets on the draught systems. He also said the breweries and craft bars were ok. The dive bars were not. Rooftop Which ones are more likely to have a line and faucet cleaning schedule? If the patios and rooftop bars have taps exposed to the heat, the bugs and critters are going to find that more to their liking, and spoil the beer faster.