All very well, I suppose, if you're that keen on saving the whales and things
Americans think locally, and this simple trick really helps keep down the smog in the big cities. If you have ever seen LA on a bad day (or not seen it
) you will know what I mean. In California, they are deadly serious about smog - they are even banning (or already have) those petrol blowers they use to keep gardens clear of leaves and other junk.
AVGAS fuel trucks don't have the same recycling mechanism, and I believe AVGAS has a waiver from all the enviromental regulations. It doesn't surprise me that at some places the EPS has come in to some airfields, but I cannot remember anywhere myself where I've seen this. In low wing planes it's easy to put clean fuel back in the tank, doesn't do any harm.