You can't have it both ways.
Public outcry RE littering. Result : Councils take pictures of people littering and attempt to prosecute them. Result : Public outcry about misuse of "Anti Terror powers". Erm, sorry, WTF ?
Children as mystery shoppers to off licences, supermarkets and pubs has been taking place for many years, but all of a sudden it's a an "abuse" of RIPA ? What about before RIPA ? Was it a terrible abuse of the human rights of the citizens of the UK before it was regulated ?
RIPA may be a poor piece of legislation, it's protections may be poorly applied, but it's hard to have a discussion about that when people are screaming about similarities to the statsi because perfectly normal enforcement activities (littering, dog fouling, fly tipping, etc) are being undertaken.
And to simply say that these should be police matters supposes a rather larger police force than we posses, but oddly, those who sing from the RIPA hysteria hymn sheet often use the phrase "police state" ...
FWIW I think RIPA is an awful piece of legislation. It's just a shame that the debate about why is so poorly framed and that the abuses that do occur are blown so far out of porportion.