It’s a different usecase, Tor is more than just a proxy. It also anonymises your browser fingerprint by making you look like every other Tor users
And even if you do fully trust Mullvad, there is still a really small risk (not important to most, but may be important to some) of them being served a gag order or a rogue employee messing things up. It really depends on your overall threat model
Yes, that’s correct. This is also the reason a lot of people in countries with restricted internet access like Egypt prefer VPNs in a lot of cases. Lots of people don’t have to worry about legitimate multi-national investigations into their internet activity, they just have to be reasonably confident that their VPN provider won’t comply with Egyptian (or whatever repressive country) investigations, which is a pretty easy ask for most VPNs.