IMO, taxes are for generating revenue and should be user-fee based as much as possible. Taxes are not for discouraging behavior; we're not trying to discourage people from being employees (income tax on wages) or buying products (sales tax) are we?
Fines are for discouraging behavior.
I hate it when people try to distort taxation for their political purposes. They are, of course, the very ones who bitch about taxes being too complicated etc.
If you don't like certain WS trading practices then outlaw them and fine them if they do it.
Fern