It is avoidance. The problem is that "avoidance" is being conflated with "evasion", where the former is not paying taxes you don't owe, while the latter is not paying taxes you do owe.
I pay the tax I owe. I avoid paying capital gains, for instance, by not being an investment bank or trading stocks and shares. I avoid paying inheritance tax by not inheriting anything from my still living parents. I avoid paying the car tax for three cars by having just one car.
This is what keeps annoying me about this whole thing: confusion of terms. Contractors only pay the tax that they legally owe, and for some reason this has become a bad thing.