In Canada, the disposal fee is paid up front when you purchase tires. This cannot be avoided. When you buy your next set, you can give your vendor the old set. They will take them if you like, and cannot charge you a disposal fee. They don’t try to weasel out of it.
Where it falls apart is when the tire purchaser takes the old tires to either sell or to put on another vehicle or save them for a rainy day. This is the secondary market and is a reality for people who cannot afford to buy new tires. In the end, those tires are illegally dumped wherever when the tread gets down to the wear bars or worse. There is a huge pile of tires at a section of our land fill right where a sign says “ do not dump tires”. The local municipalty pays to get rid of them which means the taxpayer ultimately picks up the tab. I’ve also see a place nearby where the tires were dumped in the bush.
A set of four new truck tires is the equivalent of between $1000 to $1500 USD so its very common for used tires to be sold in the secondary market.
The law here is that a M&S tire is legal for winter driving if has more than 4/32 “ (3 mm) of tread left. For me, that is a unsafe amount of thread in the winter but to each his own. However, it’s probably OK for summer use. I would suggest that a set of tires left on a curb will be taken if it has 8/32 of tread left and in some counties I’ll bet they will be picked up if they are any amount above the wear bars.
For comparison my latest set of new All Terrains have 16/32 of thread.