The difference being that (in all cases I'm aware of) you get some sort of representation in the HOA (ie voting on things). Also there are almost certainly limits in any given jurisdiction on the sort of rules an HOA can impose.

One reason for this difference is that HOAs are kind-of eternal. They need some way to adapt to changing circumstances. Whereas things you will only use for a few years, you get to vote with your wallet. (As you do when booking a hotel, or renting an apartment.)

HOAs are becoming ubiquitous. In my area, nearly every home built in the past 20 years is under a HOA, and of course there are older HOAs too. They're generally created by the home builder, not the home buyer.

When I was buying a house, I didn't want an HOA. I hate them. But the options were extremely limited, and it was a seller's market.

I think local governments like HOAs because they pay to maintain certain common areas, so the cities don't have to spend tax money on that. Also, local politicians are all on the take with... surprise, surprise... the home builders.

So when I buy an iPhone I get a seat on Apple's board like I do when I join an HOA, right? I can vote on whether they should change these policies?

In practice, it doesn't matter. Your share would be so tiny that voting with your wallet is equivalent. After all, people usually renew their phones every few years.

By that logic let's get back to monarchy.

Are you serious? HOAs not only do not prevent obnoxious neighbors, they virtually guarantee it.