Yes, there are employers who will shake down a community for anything they can get and who will regularly threaten to pull out.  However, if you are maintaining a good relationship with all the employers in your area of operation, you'll know who these are.

And you will concentrate on the ones you can really help.  After all, if a new plant comes to town and brings fifty jobs or an old plant you have treated well expands by one hundred jobs, which looks better on your resume?  

It is all about preserving jobs, high quality jobs, from friends old and new.