Dog poo.....

Why do dogs produce so much faeces..? My dog produces about 4 lots a day, which I bag up and put away in a bag in the bin... This brings me on to why do people not do that in general...? Where ever I walk the dog, I always nearly step on or sometimes trip over a steaming pile due to some ignorant, lazy individual not cleaning up after themselves. Its not difficult, but to some people with big dogs especially it does seem so. And then the signs, loads everywhere indicating a fine for not picking up. Well I have not seen it enforced yet. But, hey with current public sector resources stretched to the limit with the austerity measures is it any reason why! So yet another of lifes petty little foibles the usual lazy, ignorant individual gets away with....