> house

I can't afford a house ($2M+ where I live), so I don't have one of those mailboxes. My apartment complex doesn't have a visible USPS pickup anywhere that I know of.

If you meant those inverted U shaped things that look like they are from WW2 (maybe WW1?), I forgot about those, but somehow I never know how frequently they are checked ... there is no indicator about when they were last opened and I wonder whether the mailman might just forget about a couple of them in odd parts of town, which is why I always feel more "secure" dropping it at a USPS.

I was once walking down the street when I saw a presumably-GenZ person who thought they were a trash can and casually dumped trash in it so there's also that concern, if everyone is using them as trash cans now ...

Even if you are in rural Alaska or something, drop boxes are checked on a rigid schedule as part of the mail delivery route. They’re reliable.

>My apartment complex doesn't have a visible USPS pickup anywhere that I know of.

They usually a slot or little door for outgoing letters, if your package was larger than that, sometimes you can leave them at the 'office' of your complex if they have one. But yeah, in your case, going to an actual post office might have been the solution if you don't trust the street mailboxes.

Most are picked up daily at a scheduled time.