Harry Bloomfield wrote
The Natural Philosopher wrote

https://www.express.co.uk/life-style...olen-safety-UK

How can a key wrapped in tinfoil even open a car?

You misunderstood...

The key is read remotely by the thief, which then allows the thief to send
the correct code to the car, to open it, start it and drive it away.

Not with rolling code systems which all cars use, they can't.

Owners keeping the keys in tinfoil, or a Faraday screen, prevents a thief
from remotely reading the key.

Keys don't get read.

Likewise, the contactless debit/credit cards, they can be remotely scanned
and the data used to make purchases by thieves. I keep my cards in my
wallet, inserted into the outer pocket of which, is a sheet of metal foil.

Makes more sense to use apple pay or google/android pay instead.
Those can't be read by anyone.