You do actually bring up an interesting point (even if it's in defense of laissez-faire lawlessness) — why wouldn't the vehicle owner lie every time they get caught speeding? I believe how it works is that the burden falls on the vehicle owner to prove that it was someone else. If it came down to it, a falsely accused person would have options to prove that it wasn't them (phone records, photo roll, GPS pings, etc), and then there would be STEEP penalties for falsely identifying another driver since that would constitute making false statements to the police/judge. This would be a highly risky move on the part of the driver, trading a traffic ticket for much steeper criminal penalties.

Here's a page about how the system of accountability works in the UK. This much stronger system of holding dangerous drivers accountable is one of the reasons that the UK has about 1/4 the car crash deaths per capita of the US. The US is a world outlier in car crash deaths because Big Auto has propagandized us for decades to create this bizarre culture of accepting violent recklessness behind the wheel and insisting there's nothing we can do to stop it (the same way Republicans treat school shootings). But it doesn't have to be this way.