Mid class issues with tax is exactly what I was talking about.
For instance, replace every social help, including unemployment pension with an universal revenue, then the middle class will get it as well, and so they wouldn't feel like there is an outrageous unbalance between what they get in return and what others have.
In our European countries we are not really aware of what our heavy social system bring to us. It is easy for us to see its cost though.
But imagine favelas in your very country, imagine 1500 murder a year in your country, imagine going from first PISA ranking to NA education : no Nokia, no Sampo no new tech companies to sustain your current GDP.
Also on a purely economic topic, don't forget that these assisted people use pretty much all their money in direct consumption, meaning almost all of their money support your economy. People paying for it are wealthier, and they don't spend all their money in your economy, a substantial part of it is invested in international companies, in saving, etc.. And all that don't support your economy. Meaning by lowering social help you will lower total wealth of your country years after year. I could enter more in details but it compensate widely the lack of competitive economy liberals claim you have.
All in all, if right after reducing social assistance, the middle class will indeed get a revenue increase. But after few years it will be all gone and will keep degrading years after years with all the social issues mentioned above.
So now, it is up to you to consider what is the correct level of social help. The correct level of inequities your society can handle. And that my friend only you can decide. But I would like you remind you to consider all the factors in stake to create your own educated opinion.