My family acts the same way, they don't recycle or conserve things such as paper, recyclable water bottles. They do not even know what goes in the recycling bin. Even when I told them about how harmful it is for sea animals they still do not care about it. I tell them to but they do not. There is nothing that I can do about this which makes me really sad.

Instead of asking them to follow rules they may perceive as too complicated, just tell them to leave everything on the counter and let you sort it. That way it goes where it's supposed to and you don't have to be mad at them.

That would drive me insane. I think you should make a chart of what do to with everything and what to buy/not buy and email it to them. Let them know that it's your house/your rules. No single use bags or bottles allowed. As for the paper towels, I have about 30 dish towels in my BnB and tell guests to please use them instead of the paper towels. People have been really good -- in general -- and I think the current roll of paper towels is about 3 months old now. I think they appreciate seeing an alternative....I've had people tell me that they were going to do the same when they got home...they just never realized having a stack of dish towels would save them using so many paper towels.

People are just not as considerate.
It's sad, but that's how it is sometimes.

Depending on what sort of people they are, they may understand more clearly if you take the time to educate them on the consequences of not recycling: show them videos of animals trapped in garbage, for instance. Some people are perfectly capable of empathizing, once they realize they are part of a problem. Just be careful about how you go about bringing it up. People don't like feeling like they're being lectured.

We have recycling bins at work. I am constantly giving my coworkers a hard time about throwing recyclables in the trash rather than walking a little ways to the bin. Some of them have finally learned that it's easier to walk to the bin and recycle than to deal with my disapproving glare.

I feel your pain. I recycle far more than my kids do. The question being do you want a peaceful visit or to alienate them? Pick your battles wisely.