State-Licensed RE agent/broker must subscribe to Realtor® brand to access Multiple Listing Service?

[Neil G.]

If so, in which states?

And if so, how does that not violate anti-trust laws clearly against monopolization?

Can't help but notice that like 99% of MLS providers' initials end in 'AR' for Association (of) Realtors®

i understand ethics requirements and good for the community and such, but arent even those intrinsic to state license issuer, not commercial brand?