The USG was wise enough to fund them when they were extremely risky.
Money isn't enough to make a search engine; Baidu for instance has the Chinese government behind it but still produces worse results even for Chinese language searches than Google. Bing's had quite a lot of funding from Microsoft put into it.
Tax payer's money payed for most of the infrastructures, research and education those companies requires to operate.
How can you run a company like Google or any other without educated employees, roads, internet, etc.
Entrepreneurs love to think they built themselves alone, but they are just a product of the society they lives in.
Now as a society you can choose to either socialize or privatise your infrastructures, but you'll have to pay for them either way.
But that funding could have came from anywhere. Just because the government funded something, doesn't mean that the thing would never be funded if the government didn't fund it.
>Thats debatable. Any blind studies?
Entirely anecdotal, but I've never met anyone who tried Bing and didn't switch back to Google after finding it flounders with more complex searches.
I'm not sure how one'd go about designing such a study, to avoid favouring one search engine by inadvertently testing queries it's more suited to (or picking people who make queries more suited to one than the other). Or how quality of results would be measured.
One somewhat empirical measure: Google has a much larger market share.