Only PhDs are paid. I think the salary scale starts at around 51,000 CHF. That's a lot for other countries but it isn't for Switzerland. The exact amount is public knowledge and you can find it if you look. It is slightly higher for ETHZ, but not much.

Bachelors and masters pay fees according to: https://www.epfl.ch/education/studies/en/rules-and-procedure... or https://ethz.ch/en/studies/financial/tuition-fees.html

Tuition is definitely not free, but also not extortionate.

Here you go: the salaries of PhD students at ETH Zürich: https://ethz.ch/en/the-eth-zurich/working-teaching-and-resea...

In Swiss federal institutes grad students are paid but it's free for undergrads.

I'm afraid it isn't free for undergrads, even outside the federal domain. Actually St Gallen is more expensive than ETH! https://www.unisg.ch/en/studium/informationsangebote/gebuehr...

Free for undergrads here meaning that they attend school for free (no tuition), or that they are not paid? Or both?

For undergrads, no tuition fees and they are not paid