Tether is an enormous fraud and the financial reporting of the reserves has just never been up to generally accepted standards.

The thing with crypto is that much like some of these other commodity markets there's less real trading volume than many people think (there's been a lot of wash trading going on: https://cryptobriefing.com/binance-wash-trading-icebergs-tip...). Where crypto is very different from the futures markets is that you can just buy the stuff directly because the costs of holding it are much lower. Say I want to invest in oil, it's a massive pain in the ass to build warehousing to start taking delivery, whereas something like crypto is much easier for a company or individual to hold. From this point of view there's very real non-regulatory reasons why trading futures for oil makes sense whereas this is not so for cryptocurrencies.