This makes no sense.
Nowadays these dogs are “exposed to those things” and still - look at the behaviour of many of them. They may have been banned from this specific shopping centre in Glasgow, but I see them in many other shopping malls, bookstores, restaurants, public transport etc the list goes on…
I grew up in the 90s and many people in my neighbourhood had chilled out well behaved dogs that didn’t invade places designed for humans such as shopping centres, libraries and restaurants. They didn’t need to be trained to be in these spaces, because most sensible people recognised they shouldn’t be there. For the sake of both the dogs and humans.
They got to sit at home with familiar faces and play in fields and walk around their neighbourhood and relax in their garden, which the dogs probably enjoyed more than going shopping with their owners for makeup and clothes.
many of the more dogs - particularly “lockdown dogs” - go to all these places I’ve listed above. You claim these spaces are an opportunity “to teach” them and yet they seem far more anxious, highly strung “reactive” and badly behaved.
I have seen people let their dogs run up to random people including me in public spaces and behave badly so no, the mere act of taking your dog in these spaces doesn’t automatically teach them how to behave. The owners need to actively train them and many are not.
And it’s not really acceptable to use public spaces as an opportunity to “teach your dog” if it negatively impacts people in the process such as having to dodge poo in shopping centres or as in the catch of OP having your picnic ruined.
And it’s all very well saying it’s the owners fault because yes of course it is, but the point is many of these owners exist and inflict their chaos on everyone. It not being the dogs fault doesn’t really help much.
We need more dog free spaces and many dog owners and dog lovers agree with this too. Not everyone needs to drag their dog around everywhere with them.