You do talk about poo a lot when you have dogs ...
In appropriate areas, I take the approach of using one bag per walk (or indeed several, cos my dogs' poo is properly solid and doesn't leave a mess) to pick up the poo and throw it somewhere very inaccessible that it is blindingly obvious no-one is going to stumble across it. Examples would include under large holly bushes on our regular morning walk, or other side of a ditch with no public access.
I re-use the bag a fair few times if there are no obvious marks (obv being very careful to not touch the inside). This means that I occasionally put one empty bag in the bin to go to landfill, rather than 6-9 full ones.
Obviously there are some areas where this is not appropriate, and I bag it and bin it, taking it home to do so if necessary.
Obviously this is not laziness, I am still picking the stuff up anyway, just disposing of it differently. I would genuinely assume that this has far less environmental impact than putting three dogs' worth of poo in individual bags in the bin on every walk?
I am somewhat concerned about those talking about effects on soil, although I rarely walk where there would be any grazing livestock and would obviously B&B if I did.