You’re not allowed to have a general-purpose tool because these companies have neglected security for twenty god-damn years.

It would not be complicated to have a wireless fob that reads an entry code out loud… and still has nigh-unbreakable security. At the very fucking least, security that’s not going to rumbled by just repeating the same numbers, later. Symmetric-key cryptographic functions are not secret witchcraft. There’s Cortex M0 chips that cost ten cents. I dunno what key length you can compute in half a second at 20 MHz… but enough. Surely. Enough so that no crypto mining rig is going to reverse-engineer it, faster than if you just sold the computer and bought the car.