First I need an exact defenition of a "chaser". If the person is on railroad property they are trespassing, unless they have permission. Permission could only be granted for a financial exchange, if that is the issue. Not a thing wrong with that.
If they are on public property - then no matter how much it annoys you (the sponsor or paying riders) that's just the way it goes. It annoys me greatly whenever another private citizen thinks they have a right to badger me off of public property. This isn't commie Russia and we're not under martial law -
Lon (Who doesn't take pictures of moving trains - it spoils the experience and who also supports financially a great many historic rail operations)