Safer Motorcycle

That seems like an oxymoron to me, the phrase "safer motorcycle". Aren't all motorcycles sort of inherently unsafe? Don't they just plain want to turn over sideways and dump the flesh of their riders' bodies onto the road? I suppose that's one of the reasons why we have started seeing those flashy three-wheeler things driving around that from almost any perspective look like some sort of cringingly unstable sports car.

Wouldn't it be safer of they added a 4th wheel to those things?

So here's my question:

Why aren't there any four-wheel motorcycles? Would that be politically incorrect or something?