The standard for this in the UK is that you should make a reasonable effort to work out who was driving.

e.g. checking your calendar/diary, looking through receipts or bank statements to work out where you likely were.

There's also a requirement that a request for information is sent within 14 days for minor incidents like speeding or red light violations, so it's not like you have to work out who was driving on a Tuesday morning three years ago.

Your car, your problem. Either get someone to fess up, or take responsibility yourself and stop loaning it out.

There really is no difference between "who drove through a red light" and "who scratched the bumper while parking" here - how do you currently solve the latter one?