In message , Andy Hall
writes

In the case of bathroom plumbing, my theory is that since the majority
of the population are right handed, they will grab first for the right
hand tap if they are not paying attention. With the hot on the left,
they will not scald themselves.

If you believe that, you'll believe anything :-)

Worse than my reply.

But my argument was better
if you're holding something in your right hand, it leaves the left free
to turn on the cold tap
--
geoff