You do not have to pick it up on agricultural land, common ground, waste ground etc....

The law only applies to areas meant for public use such as parks, playing fields, pavements, grass verges but only those next to roads with a speed limit of 40mph or less. I've read up on it.

The dogs did their business on fields where the law does not apply. Wild foxes do their business in the same places so whats the difference?
I do walk them on a playing field but always walked them elsewhere first so they could do their business before going to play fetch with the ball.

Like I said, dogs kept in the house have to hold themselves every night of their lives...and often for lengthy periods during the day when their owners work or have to go somewhere the dog can't go.....does it kill them?