@Zach269 You could always add the $25 as a one-time fee, due at booking, for removing the garbage, explaining that it will be refunded if the guests actually do as instructed and take it to the drop-off site themselves. But you'd have to have your housekeeper snap a dated, timed photo of the garbage left behind before another guest checked in, otherwise a guest could claim they removed it and argue about the refund.
Do you have any neighbors in the area who you could offer a lesser amount, like $10 to, to stop by and pick it up, since they have to take theirs as well. How do the other Airbnbs in the area handle it? They must have some non-compliant guests as well. Maybe you guys could get together and pay someone to drive around the neighborhood and collect the garbage from a lot of you.