Where did all the patents go

Where did all the patents go?
Products are seldom patent marked
On November 4th, 2009 Anonymous (not verified) says:
I am an old engineer. A couple decades ago, just about every product has patent numbers or "pat. pending" notices on them. The lowly light switch had patent markings.

This practice seemed to have fallen out of favor in recent years. For example, my new HP laptop has no patent markings on it, nor in the paperwork. In fact, I have gone over every gadget I purchased recently and none are patent marked.

Can you comment on the divergence between the law and actual practice?