Then you're mostly looking at those who "try" - but if you look wider you'll see polls used way more often than that (think of the companies entirely built around it, customer satisfaction surveys, Facebook "polls", etc, etc).

Doing a proper poll is expensive and (frankly) most of the time is pretty predictable or you can get 90% of the results with 10% of the effort, and most times you don't actually care about the results because you're building it to get a result you want anyway.

(Interestingly enough elections themselves almost by definition have notable discrepancies to a "true" perfect sampling; but it's usually overcome by the sheer volume.)