Email is not carrier and is not regulated as such. I can create a private mail server, invite users and keep any email from being delivered that I so choose.
Ridiculous idea. Sure, you can run your own private email server... and watch as your messages go to everyone else's spam. It does not matter what SPV, DMARC bullshit hoop you jump through. Ultimately google gets to decide what email providers live and what email providers die.
It is analogous to creating your own postal service or phone company that only lets you send letters to users of the same postal service or phone company. The service is only useful due to network effects.
But it actually is almost impossible to truly start your own phone company, in terms of running wires to people's homes or putting up towers. The capital expenditures and regulatory hurdles are near impossible, save for extremely well financed and well connected people.
I've had SMTP servers which have extremely high deliverability rates hosted for <$100/mo for over a decade.
The capital expenditures are nowhere near comparable. The regulatory burdens are nowhere near comparable.
Email providers are not common carriers. Its very easy to just sign up for a different email provider. Its easy to buy a domain name and update MX records across literally hundreds of commercial providers eager to have your business. And even if every single host bans you (you really should then question what you're doing if nobody wants your business) its still technically possible to go it on your own. And once again, as long as you're not being generally abusive its possible to have good success.
Comparing getting banned from Gmail might as well be the same as comparing getting banned from McDonalds. McDonalds isn't a common carrier no matter how much you like Big Macs. There's plenty of other restaurants available.
