They can. But it's centralized, custodial and has limited to merchant which accept Visa debit without strict limitation. By strict limitation, i mean only accept card from reputable issuer. In addition,
1. There's concern about fee and conversation rate which might feels unfair for the user.
2. Such service only available to user in certain country.
well, i'm not a big fan of using something like coinbase's crypto debit card for the simple reason that i don't feel a coffee purchase at starbucks should be something i should be needing to keep track of and report to the IRS. so i'd just open a throwaway checking acct that I can put a small amount like $50 or $100 and use a debit card on that account. that beats using bitcoin to buy coffee by far. and makes more sense. and no i'm not worried about my bank shutting down and taking my $50 or $100 with them.
with something like the coinbase debit card,
buying coffee at starbucks = you sold crypto and need to report that on your federal tax return so the irs knows about it..
but to tie it back into the discussion, there's just some things that bitcoin can't do. it can't be everything to everyone maybe it can't be the solution to buying tiny things like a cup of coffee. not as time goes on.