Well, take Second Life, VR Chat, NeosVR, Resonite, etc. They all are pretty similar concept-wise. First thing you get is a login screen. You need an account. On some, that account costs (or used to) cost money.
The world is locked inside a walled garden. If you don't like SL's rules, you don't get to touch anything SL related. You can't talk to your SL friends without logging into SL.
The server code is closed source. You must use the central infrastructure. In some cases, like SL, the client is open.
They sell add-ons like storage space for your stuff, and things like avatars you can directly buy. Some have an internal economy, but eg, Second Life quickly moved to being the official owners of the internal marketplace, and tax transactions.
If you want to have a permanent chunk of the world in SL, you pay for that, monthly.
All pretty standard. Now compare High Fidelity.
You install the client, open it, and instantly you show up in-world with no login screen required.
For data storage the solution is to pay any random web provider, or use the free AWS S3 tier. Any asset is just an URL pointing to https://example.com/file.gltf -- served from any random server, downloaded client-side, and outside HiFi's control.
Okay, so you pay for hosting your own environment? Nope. You host it on any Windows or Linux host you like, or the installer will even automatically install a server locally, easily start it from a menu, and NAT hole punch so you can host stuff on your laptop if you want to.
Tax Alice selling stuff to Bob? Well, the system is so open that anyone can set up their own shop if they want to. The source code for the shop is open, so is both the server and client. Since assets are hosted externally, nothing prevents Alice paying Bob with Paypal, emailing a file, and escaping any taxation.
Excluding people who break the rules? No such thing, there's no "grid". You can only be banned from individual worlds, like HN blocking you off doesn't mean anything for Ars Technica.
And all of that was Apache 2.0 licensed, so anybody who wanted could absolutely set up their own commercial operation and not share any of their own improvements.
If it was me running it, I'd have put the AGPL on it to discourage competitors, and either focus completely on custom setups for whoever needs one, or try to run a very light operation subsisting from Patreon.