Pamasich

that blocks your bank or even some games if your phone is rooted

That’s your bank and those games, not Google.

The games are obviously afraid of cheating/hacking. For the bank it’s about your account’s security. Root access gives a lot of power to potentially malicious actors, it’s definitely not weird for them to not work if your phone is rooted.

Antitrust is about powerful companies abusing their powerful positions. With powerful I mean control over a market.

The idea is that if society is functionally dependent on a product, it shouldn’t be the case that the owning company abuses that position to force people into walled gardens.

While it’s of course still bad if a smaller company does it, the amount of people impacted will be lesser, so it’s not seen as critically important to take action against it. So that’s why antitrust laws only target the big ones.

I do absolutely disagree with Apple not being big enough though. iOS has a 30% market share in the mobile OS market according to statcounter, that ought to be big enough imo.