It wouldn't cost them too much, they just don't have an incentive. They've got a virtual monopoly on the search market. If there were 5 different search engines with market share split between them all, you can bet that they'd either need to provide superior support or superior margins to maintain their market share.
This is a symptom of a monopoly, not a symptom of the market/an inability to make money while providing support. I mean... let's get real, look at their quarterly income statements. There is a LOT of wiggle room to hire support personnel,