Make the support request cost $250-$500. Guarantee a human on the other end. That drops spam/scam attempts down to basically nothing. It also helps cover the cost of providing real review. Plus, $500 is a very reasonable expense for most companies (basically negligible for all but the smallest), and it's a high bar for scams/spam.
Basically - No, your answer is not a valid reason to not provide human based support.
So charge them less? Now the scammers will call from those places.
How does msft handle support contracts from customers in the developing world?
As far as I know it's priced the same. In the context of this discussion - A business to business relationship - $500 is pretty reasonable at a global level.
For an individual consumer - I think $500 is a fairly steep price even in the US (and other 1st world countries) and that's by design.