To be fair, my last apartment in NYC was like that. Convenient trashcan right in the mailbox room. Though I suppose my mailbox didn't literally get filled daily. If that's the case in Japan, that's pretty bad.
This drives me crazy. Greater than 90% of our mail is junk mail and goes straight into the recycling bin. I was watching some recycling process videos the other day, and when it came to bailing up the sorted paper, it looked like it was basically all junk mailers. We literally have systems that supply time and money to design the mailers, supply ink and paper and probably some plastic to make them, mail them, pass them around in the mail system, deliver them, then they're promptly thrown away or recycled, then they're carted off to be processed, and then the mailers eventually end up in landfills or partly recycled. It's insane. It's a closed system that does literally nothing but expend resources and output emissions.
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.
In the Netherlands we have stickers you can stick on your letter box that stop 99% of unaddressed spam from being put in. The sender can get into trouble with the regulator if they don't adhere to this system.
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.
This actually works in Japan too. I'm not sure if there are regulators who have your back here but I've been using a "no spam" sticker to pretty good effect.
At least in Sweden those stickers only stop the unaddressed leaflets or catalogs they put in the mailbox. If someone printed your name and address on it, the junk will still be delivered.
In the Netherlands too unfortunately, and this is being abused on a small scale by companies with bigger pockets to just purchase an advertising package from the privatised Dutch post (PostNL they are called nowadays), and have them deliver spam with your address and 'to the residents' on it. It's a spam loophole politicians so far have refused to close, and which PostNL defends as being perfectly legal and part of their business offerings. I think I get one of those each month — it's much more expensive to send than normal flyers.
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?
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.