The principal effect of choice has been more to preserve the city's private schools, many of them Lutheran and Catholic ones, than to create schools that innovate or reform
In other words, the money is doled out without much checking from the state, money that could have been going to improve the local public schools.
Based on firsthand observations and other reporting, Journal Sentinel reporters concluded that at least 10 of the 106 schools they visited appeared to lack the ability, resources, knowledge or will to offer children even a mediocre education. Most of these were led by individuals who had little to no background in running schools and had no resources other than the state payments.
You can read the article here