Lots of great comments here but one more awesome thing about wooden cutting boards - you can always sand off a very fine layer to expose new wood if the surface gets too gnarly. Then oil it and use it like usual again.

And plenty of butter and seasoning.

There’s poop germs on basically everything everywhere all the time. Life’s dirty and you have an immune system, don’t overthink it.

If I had to guess, it’s because the back/top of the fridge is more prone to freezing.