Either you use Apple Pay with a fingerprint, or you have to enter credit card details and press a button that says “Pay $4000”. This is impossible to do by accident.
I think this could be solved by making the user input the expiration date of their credit card manually in the checkout screen. This is very common practice in ecommerce for this very reason. I also don’t understand why the pay with credit card button doesn’t look like a button. That’s just bad UX.
All that said I do think some of these reports have to be buyer’s remorse because I don’t understand how this extremely particular series of accidental inputs (pocket or otherwise) could have happened to as many people as are talking about it online. However, it does seem possible that Tesla could charge you up to 10K without your consent which should be fixed immediately.