Mopooghai72 Can you just get on trains in Switzerland without seat reservations as you do here in UK?
Yes exactly, that‘s what everyone here is doing. Seat reservations are so uncommon, that we‘re not used to check whether a seat in an IC is reserved before sitting down, let alone minding carriage numbers. So if reserving a seat, you‘re very likely to encounter the slightly embarrassing situation having to chase someone already sitting on your seat away (who wasn‘t aware).
If checking the red 3 persons symbol, you already have a huge advantage over the vast majority of your fellow passengers and therefore could head at carriages at the end of the train, where the choice of still free seats is usually much better!