windshield wipers

When I was in flight school I asked why GA aircraft don't have
windshield wipers and was told that it's because the prop blows the rain
off - really - that's what they told me.

Now I fly lots in rain. This past 2 weeks I have flown in more rain than
I ever wanted to see - and the prop definitely doesn't blow the rain
off.

So I'm back to my original question.

Why don't GA aircraft have windshield wipers?
It can't be cost - even the cheapest Yugo/Hyundai/Lada have windshield
wipers - but not a $250,000 aircraft.

Anyone know why?

--

Tony Roberts
PP-ASEL
VFR OTT
Night
Almost Instrument
Cessna 172H C-GICE