My complaint is the feeling of being forced to use them when they are the dirtiest and most dangerous part of the road. They are just dashed white lines that were designed by someone who drove down the street in a Transit van once.
Since I've been moved to WFH I exclusively cycle on country roads, I feel like if we had more segregated bike paths in the city I wouldn't mind being stuck behind people, I feel like commuting or cycling into town is a different thing from cycling for exercise or as a sport.
I live in a country where cycling as a mode of transport is basically non-existent, 95% of the people I see on bikes are on road bikes and wearing lycra, so it's possible I'd feel differently about segregated lanes if there more of a cycling-as-transport culture here.
Yes sure this is an enforcement issue I guess. Why not just build a physical barrier that doesn't require enforcement though.