There are alternatives that don't require centralized VC funded startups to act as banks for these cases. One would be: Having a mini wallet on paper (QR code for easy handling) and paying from that in your bar.
How can you have a paper wallet to make transactions? That would require the wallet to expose its private key to the recipient so they could generate a transaction. That means the wallet is compromised on first use. Paper wallets really only make sense for two things: carrying an address that others can send payments to; carrying the private key so that you can transfer the full amount into some other address.
