Both auto-forwarding and auto-reply are paid features, which makes cancelling & switching much more difficult. Gmail is a breeze comparatively. I highly recommend against using their addresses (e.g. protonmail.com, proton.me, pm.me)
Email forwarding is available for everyone with a paid Proton Mail plan.
(source)
How do you expect anything to be completely free?
Point seems to be that people are switching from gmail to proton for free email, but it’s going to be even more difficult if Proton becomes like Google turned out since you’ll have to pay to get all the email to your new address while you are transitioning to whatever is next. Instead go to that next thing now before you get “locked in” by having all of your important emails going there. With gmail at least you can forward the emails for free from the places you forget to change your email with at first.
Removed by mod
A better question would be, why do domains cost so much.
Domains cost like $1 if you’re flexible. Email hosting is what costs money.