I have already demonstrated that Smith favored a proportional tax system, not a progressive one. It is in Smith's own words and SixOfNine does not have a leg to stand on.
I see SixOfNine went back and edited his first page post with quotes after he was called out for producing nothing.
Here is one of them:
"The rich should contribute to the public expense, not only in proportion to their revenue, but something more than in that proportion"<109>
Full context and notice how SixOfNines dishonest truncation changes the sense of it:
"The necessaries of life occasion the great expense of the poor. They find it difficult to get food, and the greater part of their little revenue is spent in getting it. The luxuries and vanities of life occasion the principal expense of the rich, and a magnificent house embellishes and sets off to the best advantage all the other luxuries and vanities which they possess. A tax upon house-rents, therefore, would in general fall heaviest upon the rich; and in this sort of inequality there would not, perhaps, be anything very unreasonable. It is not very unreasonable that the rich should contribute to the public expense, not only in proportion to their revenue, but something more than in that proportion"
Notice how Smith thought that "perhaps" it would "not be unreasonable" to institute some sort of a luxury tax.
Unlike his other statements about proportional taxation, Smith is far more tentative here. This is not a positive assertion on Smith's part, in contrast to his other statements. And either way, it is not truly progressive, since it is proportional on the house-rent. This is essentially a luxury tax on housing, not an income tax.
Around here, with a homestead exemption sufficiently large, less wealthy owners of small homes may pay no property tax at all. Above the threshold, although the exemption still applies, a percentage based property tax rises proportionally with the value of the home. This is not a progressive tax, since everyone gets the exemption.