I work at a startup trying to do this (Ethereum rather than Bitcoin): https://unlock-protocol.com/about/ https://unlock-protocol.com/about/ Transaction fees ar

I work at a startup trying to do this (Ethereum rather than Bitcoin): https://unlock-protocol.com/about/ https://unlock-protocol.com/about/ Transaction fees are there, but don't have to be enormous. Our code can also optimistically unlock the page under the assumption that pending transactions will eventually go through, so block time is also less of a concern. Right now the tricky thing is that it requires a browser extension if you want to transact directly with crypto (or use one of the few browsers that come with a built-in web3 wallet). We also have a managed crypto wallet service that allows people to pay with credit cards, but it isn't widespread because it can only be used to buy keys for locks we have approved.