No surprise that a poll sponsored by a pro-school choice group found that a majority of Milwaukee people polled favored expanding the program by removing income limits for eligibility.
Why wouldn't they want to get it on it, too, if there's "free" money to send their kids to private schools -- or to pay for the ones they already attend?
Part of the rationale when choice started in Milwaukee was to give poor families the same choice of where to send their kids as higher-income families had. Many rich and middle-income people were already sending their kids to private schools, as public schools became more and more a place for children who had no other choice.
Taking off the income limits, in many cases, will mean that government vouchers will pay private (often religious) school tuition for families who now pay it themselves, and can afford to pay it.
Granted, not everyone who supports choice has school age children. But certainly the idea that their own families could get it on it would be a big motivator in answering the question.