In practice they do?

Last time I checked, there were significant "limitations" (to be charitable... that you could only redeem holdings above $100K, only if you were a non-US person, and subject to 90-180 day holding periods.

People have also offered bounties for proof of people having redeemed Tether, and those bounties are still outstanding.

My suspicion is that if anyone has actually redeemed Tether, they are either institutional (and Bitfinex doesn't want to piss them off) or an insider/"friend".

Institutions are happy to provide arbitrage on tether -> any other crypto since they can redeem. Sure there's an extra step involved, but there's essentially no difference between selling to an institution for $1 of crypto and redeeming for $1.

The founders of CMS holdings talk about redeeming tether all the time. It's literally just the same as redeeming USDC or any other stable coin. And before you say they're insiders, Dan (one of the founders) used to work with the creators of USDC.

So they're an institutional investor. Like I said.

An institutional investor with ties to their biggest competitor, bit different.

Yes and no.

Yes, USDC and USDT are different "securities".

But that's like saying that in the regular market that because Charles Schwab and Fidelity are competitors, they don't have a whole lot of cooperation - they do, because at that scale (and with the amount of arbitrage and speculation in crypto), you need to cooperate with your competitors, or you will be iced out.