Bitcoin ATM and tax consequences

I just found that local bitcoin ATM allow you to buy crypto up to 900$ per day by just giving name and phone number.

So without id or SSN - how would they report your cost basis to IRS? so in future when you want to sell and convert it back to cash - with some capital gain - how can you calculate capital gain? and pay taxes?

 

I am not sure why they would allow you to buy crypto without ID or ssn up to 900$

is there some kind of law that you can use cash up to 900$?

What am I missing here?