Yeah, you should be afraid.
I'm way more afraid of Pprune than I am of being refused flight following.
The traffic density in the Bay Area (or LA, or the Boston/New York area) is WAY higher than anything you'll find in the UK. And my point is that TIS/TCAS/TCAD/ADS-B/whatever you want to call it is STILL extremely effective and valuable, whether or not you can get flight following or the equivalent.
The same problem would apply to your TIS if you made transponders mandatory
Same comment applies. In all heavy traffic areas in the US (in every Class B veil, i.e. 30 miles around every major airport) transponders are mandatory. Not a problem. There is a lot of special pleading going on here.