Tether is typically used on non-US centralized exchanges, where they don't have access to USDC.
People could still use USDC on-chain. According to https://ultrasound.money/, on the Ethereum network, there's $39.277B USDC and $32.35B Tether. Tether's popularity might be different on other networks.
Self plug, but for most chains you can check out https://stablewars.xyz/ to track stablecoin market caps across different chains. We show $29B tether, but difference in values for Ethereum are likely because we discount uncirculated funds, e.g. bridged assets.
It's not necessarily up to the individual. It's the centralized exchange's decision to offer it.
I could be wrong, but I think the exchange needs to work with a US-based bank to process USDC redemptions/withdrawals. I know this was the case for Binance recently.
Any stablecoin is just a company that holds the denominated value in some form, and provides the ability to get that value back. Circle manages USDC. They have to bee more willing to work with partners abroad. Is that because of KYC/AML laws? Not sure.
Tether has been willing to work outside the US before Circle, and they did it back when crypto was demonized by all banks, more-so than today.
Also, I mentioned in another comment how Tether is used for settlement on derivatives. I don't know of that happening with USDC anywhere.
People could still use USDC on-chain. According to https://ultrasound.money/, on the Ethereum network, there's $39.277B USDC and $32.35B Tether. Tether's popularity might be different on other networks.