While I agree with you 100% on the environmental side, we're being forced through mussel inspection stations for almost entirely economic reasons. There in fact have been studies comparing estimated costs of different management/non-management strategies, and they mostly end up with conclusions like this one:

"Without public management, the expected net economic impact from zebra mussels is a loss of $244.1 million over 20 years. Public investment in prevention and eradication will reduce expected damages and generate a net expected gain of $188.7 million."

Sucks for us, but it's hard to blame a water management agency for managing it's costs correctly. Anyway, I only spent a few minutes in google looking at case studies, maybe there are more encouraging ones out there.