It feels like about one time in three, but I haven't kept careful track. Car servicing, I don't know, because I only interact with the service representatives most of the time, not the mechanics; those have not only been male every single time, I haven't even seen a woman in that role (probably 100+ samples by now), though the cashier is almost always a woman (80%+)--the gender stereotypical roles in auto servicing seems stronger than anything else I've seen anywhere. I haven't called enough plumbers personally to have an adequate sample, because I tend to do simple jobs myself. One of my better friends was a woman who did landscaping, and she was the only friend I've had who does landscaping. (She was really good at it, too. Heck, if you could reliably get people like her, landscaping would be an entirely different thing--really careful attention to landscaping goals, with vegetation chosen carefully for beauty, suitability for cliimate and soil, and maintainability, rather than piles of mindless and oft-destructive busywork on whatever living thing happens to be around or easy to try to stuff in the ground. The male landscapers near where I live managed to kill a healthy, mature tree during routine pruning, replaced it with a second tree that did poorly, and replaced that with a dead stick (was supposed to leaf out in the spring--nope, it's dead).)

My eyes are open; I just see somewhat different things than you do. This could be a consequence of where I live, what I pay attention to, or just random, given the comparatively small number of instances.

This is why I rely instead on statistics, and also why it's especially vexing that multiple sources that ought to be fairly reliable can't seem to agree to within a factor of two.