In the UK, dumpster diving will earn you a massive fine or even jail time as it’s classed as “theft by finding”. Yes, that’s a real thing.
Some of our supermarkets even ensure their dumpsters are in secured areas to prevent it altogether. (Compare that with France where I’m told the law requires that unsold food be given to charity).
In our neighbourhood, however, we’ve found the best way to dispose of unwanted furniture isn’t to try selling it (usually doomed to failure) or donating it to charity (the same) or paying to have it taken away (ugh). You just leave it in your driveway and someone will “rehouse” it. We have been both givers and receivers under this unofficial local policy. Weird but it works. There’s even a strange feeling of rejection if no-one takes the stuff you leave out.