Bargaining with a toddler ain't gonna work, not in my house at least. And getting in the car and heading home if the toddler didn't stay put?? When on earth would a mother get the shopping done not to mention the time she'd waste going back and fourth to the car or to and from the shops!

I agree with the other posters, I just don't get the problem with a harness when we happily strap our kids into prams, trolleys, high chairs and car seats daily. It just doesn't make sense to me that they are so offensive to other parents. I understand non-parents not 'getting' them and how good they are but not other parents. They just aren't that different to all our other 'strap-in' devices we use as parents.
I can honestly say I bargaining works with both my girls 95% of the time. Very rarely do I ever have to leave the shops due to misbehaviour. Actually I rarely have to bargain with them either. We talk about what we're doing down the shops, things we see etc, that keeps them happy and busy normally. Normally they only play up when they are tired or out of sorts.
This morning I took both girls down the street, we went to the supermarket, through 3 large busy carparks, then to 2 video shops. They both held hands, they both walked by themselves and stayed within their boundaries. There was no bribes. Both were good.
Personally I don't think of it as wasting my time or energy, Im teaching my girls that there are ramifications to their actions even when they are outside of the home. I would rather do that than put them on a harness, actually I would personally use all other options before the harness! May I just say we have rarely used a pram or stroller even since birth. Even trolleys are rarely used, normally if I will be in need of one. Since both girls could walk they have held hands and walked down the street, our pram and stroller are only used when we go on long walks etc where the girls are likely to need a rest.
Oh and yes as a parent I do find using a harness offensive. Thats my point of view, thats how DH and I feel as parents, as adults.