Providing another revenue source has not been proven to lower income tax

It can be used to reduce the income tax.

even if it did, that would not make this source better than any other, or even better than income tax itself.

It would be better than the income tax because the income tax discourages making income, which is bad.  The junk food tax discourages buying junk food, which is good.

Aside from it having not been proven to be immoral by any standard, if it needed to be punished it would make more sense to criminalize it.

In the situations for junk food, it makes more sense to tax it then to punish people with a $500 fine for eating it because of the following:

-More revenue is raised for the government.

-Punishing it with a $500 fine wouldn’t even work most of the tie the same way most speeding crimes don’t result in fines.  Police aren’t omnipresent.

-It is cruel and unusual to punish someone $500 for eating at McDonalds.  It is not cruel and unusual to implement a tax of 20% or something like that

-A tax is essentially punishing purchasing with a very small fine of only $1 or some similar number.