We're on our third state school system.
Uniform costs (inc. logo'd polos & sweatshirts) in the UK and various small fees for PTA type stuff. A few trips, I don't recall them being very expensive or frequent, but dc were fairly young. No costs for clubs etc. School dinners were rubbish so we did packed lunches for all of us.
In the US we were required to provide a whole bundle of stuff each year (including things like tissues and hand sanitizer, as well as pencils and paper) Expensive and a hassle to get. Also various small fees for PTA stuff. I think there was just the one trip, and it was fairly cheap (we were only there for 6 months). No uniform.
Now we live in Canada. At primary there was lots of fundraising activities but very few other costs because the PTA funded lots of it. In the last two years there was a residential and also skiing (but this is local so cheap). Most families opted for one or the other. I think it was $100 for three days (which was very good value). No uniform, and the only other school requirement was for indoor shoes in winter term (very snowy here).
At secondary we have to pay a fee at the beginning of each semester (two terms here) which depends on the course. Think it was $60 between my two this time. No uniform, no other kit required. School bus is free so long as you go to the local school (95% of children do), but we pay for bus passes as the times aren't great, that's $100 a semester. Very little fundraising, except for the food bank, which tends to be about bringing in no perishables and are totally voluntary (eg they did a 'scare hunger away' event for Halloween). School trips are rare, voluntary and a big deal (eg next year if ds wanted to take biology he could go on the trip to Hawaii).
Making families pay lots of money for uniform and kit is a hidden cost I think becasue it is totally unnecessary and also unavoidable as most people don't really have much choice of school.