Why are public swimming pools so ... public?

Distance: 450m
Breaststroke: 3
Crawl: 15

Although I'm getting better at swimming again, slowly, I'm still not good enough to go in the laned off section. This is for fast swimmers who go up and down, up and down, up and down. I go up, have a breather, go down, have a breather, go up, have a breather ... and so on. If I were to go in the fast lane, I'd get in the way. So I have to try to find a lane in the main part of the pool, and share it with everyone else who is doing half widths and zig zagging about across the lanes, and generally bobbing around in my way when I'm just trying to swim up and down... Ok, it's a shared space and I accept that. But when I'm swimming in a straight line, and someone cuts right across in front of me, and I have to take evasive action, why do they give *me* a filthy look? I'd checked that my "lane" was clear before I set off, why can't they check if they are going to get in someone's way?!

I guess in a month or two I may be fit enough to use the sectioned off area, and then it won't be a problem...