I wish the government would make it illegal to mail advertising mailers. But then the USPS, which has had funding purposely cut by those who want their privately held investments to win out in the postal game or just hate anything that is available for everyone, probably relies on a lot of the revenue that comes from those mailers. So it continues.
I've found it's basically impossible to get rid of receiving them.
It works really well (it has existed for decades), and many municipalities are now moving towards making this 'no sticker' the default! This means that if you want flyers, you have to put up a 'yes sticker' instead of having none, and without a sticker you won't get any. This opt-in approach has quite an impact on the amount of useless paper pushed around.
We don't have that in the US since it's part of the business model of the postal office or USPS to deliver ads in your mail box.
I've started an experiment with these: I just repost them in the postbox and see how many times they come back to me. You can always put them in the postbox with a 'return to sender' on it, but if you leave it as is it seems to come back to you like a paper boomerang. I've had one round-trip now for UberEats; I wonder at which point it'll get taken out of circulation?
With postage, letters still get delivered reliably, and postal workers seem fairly paid, but the parcel market is a cluster fuck of a small number of international parcel companies (some home grown from our former national postal service) that have done exactly what economic laws permitted them to do. They are somewhat regulated and high profile, so they came up with a system where subcontractors hire the actual delivery guys and own the vans and stuff (all in the parcel company's livery of course), and the parcel company pays them for each package delivered. Gradually the pay got worse due to competition, and those subcontractors that can survive either get paid too little under increasing pressure (due to covid leading to more packages ordered), or, as happened in Belgium this year, they hire illegal aliens and underpay them.