Adopting it as a legal tender is just a means of them to at least get something out of the people that are using it. Imposing strict KYC laws to many crypto apps like the ones I have been using here in my country so that they would trace me anytime is one example.
I know my example was not about "adopting it as legal tender", but you get the idea.
All cryptocurrency exchange nowadays should applied with KYC procedure and many countries have make this decision needed for all domestic exchange market, maybe this way how keep away with money laundering.