I think it's for keeping the washing machine's contents (and DW and TB)
safe from potential damage caused by small fingers daytime. The top
switches don't attract their attention unlike the cute 90C
boil-my-coloureds button. They play daytime near the machines but can't
start any cycle before the Hand of Daddy intervenes. Then when they're
tidied to bed, switch on and run the units.

My theory anyway.

Good theory ! our grandson has just discovered the delights of the kitchen.

Dave

--
For what we are about to balls up may common sense prevent us doing it
again
in the future!!