Yeah, I rode one for years when I was younger but stopped due to issues with my knee. I ride a dutch style bike with an internal hub on the rear these days, but do miss how the track bike is so light and fluid once you're used to it. It becomes like an appendage instead of being a bike you ride.

For anyone unfamiliar the reason they're popular with messengers and such is in urban traffic it becomes very smooth and simple to keep pace with the cars surrounding you. And some people just ride them because they like doing the skid stop or bar spins or such. These days messengers favor hot rod e-bikes though because they're just dramatically faster and that directly corresponds to more income.

Tried the same in Norway, the hills absolutely destroyed me haha. Going up was hard because of no gearing. Going down was even harder, a struggle of working against the pedals to not spin too fast.

Didn't they get banned or there was a campaign to ban them after someone was killed by someone riding a fixie, in London?

This was mostly a fashion thing though, super dangerous and illegal in traffic to boot. You really shouldn't drive a fixed gear bicycle in traffic unless you have at least one and better yet two additional brakes. But according to purists that spoils the lines of their bikes, apparently fashion trumps safety.