Didn't realise it was a requirement to live in Southampton to support saints... someone should've told me I wasn't welcome when i spent 10 years driving to every home game from Kent and Sussex
As you say there'd be no way of distinguishing whether they are streaming something illegal or something legal like iPlayer etc.
The only way to resolve the situation as far as I can see is for the premier league to offer a reasonably priced web subscription service, showing all 380 games to compete with the illegal streaming services.