Fuckinnn black locust. You're talking about places off your property right? Rough.

One thing is spreading awareness that non native plants are bad and invasive plants are majorly damaging. I think focussing on native plants in someone's home is a great angle. Gardening is something actually in people's control and thus something they would be willing to consider. Notable points I try to get across:

• your local amazing bug (e.g. monarch butterflies) will all die without the specific native plants they need to survive
• pollinators love native plants more than non native
• Native plants are far more interesting than whatever you get at the garden store for looks
• Natives are dumb easy to maintain. Especially if ppl just buy partially grown ones. Just help it establish, in mostly the right area, and they will thrive
• It's good for the environment. Non natives cannot support our ecosystem and actively damage it.

Beyond that? You'd have to also start specific campaigns against specific invasive plants and go do group attacks on those plants. Your local green organization will usually be good for organizing and getting volunteers, as well as navigating where you can actually go. It's a big effort and a lot of work, especially for such noxious plants like full grown trees. But it can make a difference over time