There are web extension that check for bookmakers that responds with 404 and automatically deletes them.
Mio
Many do not run their own email server. It is just too hard. Companies choose Microsoft or Gmail to host email as it is cheap for them or included in something like office 365. Google have admitted that they read users' email in search for custom advertisement. I would assume the same is true for Microsoft. On the inside we just have to trust them that they don't make too many copies to foreign power or abuse it in any other way.
On the private side(not companies), Gmail really dominate. Very many don't even know what selfhosting is and even fewer have the know-how and actually do it for email. People just don't want that burden of selfhosting, maintenance, work. I would love the world to get more decentralized, use peer to peer, but today everything is more centralized than ever before.
Email should be E2EE, but that is never going to happen without the big players on that train - they just have too huge market share and that would go against their profitability.
Emails controlled by the government? No, never. Emails are a decentralized protocol and there is no point what so ever to have the government controlling it. Look, emails are not safe, not encrypted. See all emails as public knowledge. If I go to their website and login to view sensitive information about me, then it is safer. Apps are optional.
If you are talking about Kivra then there are private companies alternatives as well. You as a user pick and choose. Personally I dont use it as I get like one letter per year and would forget to login to it. There are better alternatives for normal letters as well.
In my country we have something called BankID. BankID, it's Sweden's leading electronic identification system, widely used for banking, e-government services, and secure logins. So I use it to login to the bank, check my taxes, hospital status, bookings etc. Basically the message itself is already on their website and never leaves them.
Subscriptions? We have RSS.
Buying something? Login to the website and see your order.
Delivery of something you bought and want to see when the packet arrives? You have an smartphone app for that. Like login to company app and view. You even get push notifications.
And for those people who actually get a message from a person instead of a company. You have chat, like Microsoft Teams, Slack, Discord etc. You even can have voice and video conference with the other person. Chat is instant messaging and is not slow compared to email.
Account registration? Make use of OpenID. Or even better passkeys.
Bonus: In my country we have Kivra - government post. Any company can get it and send the normal letter in a digital format - basically the none printed version of the letter so a PDF.
I don't want to fall for ads. I use price comparison webpages and can there monitor for specific items and priceranges.
Alternative you can often view their ad campaign on their website and in PDF format.
There are special smartphone apps that just collect ADs. Basically the provider put their PDF there. Just subscribe there to what you want.
Some people even prefer the paper version.
I would make sure the family car accident don't happen that year in October. Next thing would be to grow up and actually try to fix the climate problem so we reach the goal of 0 degree higher temperature on average. Imagine having 30 extra years to spare for this task. Telling how much damage it already have done and we have enough evidence that it is critical to start doing it now.