In a garage used to store a car no real problem, even in a garage which is used as a store room no real problem, however in a garage used to repair cars in, then there is a reasonable chance cables can get damaged.
Protecting with plastic seems pointless, and steel conduit is not easy to bend and needs proper benders, the Germans free air the bends, and just use straight lengths, and to be frank you only need protection low down, so a switch with a meter of conduit up the wall and a stuffing gland would likely offer enough protection.
What you need to do is a risk assessment, written of course, if you show you can considered the risks and taken appropriate measures, should a unexpected thing happen you can show the courts you took reasonable steps, so likely you will not get blamed, if you can't show with paperwork you took reasonable steps, then you have a problem.
In a garage with fork lifts running around a 2" round steel barricade around junction boxes was considered as required, but would not fit them normally, fork lift drivers are blind, other wise we would not need to wear hi-vis.
But a car also has blind spots where you can hit a wall or post because it is too low to see, so simply keeping wiring above waist height will in the main keep it out of harms way, it's only common sense.
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