AI is nowhere near being as good as the brain of a labrador. Also the blind person has to be able to trust the guide and it has to be adaptable and capable of recognising unusual threats. The auto driving AI's fall down at that point and they have more sensors and heavier computers than spot could usefully have.
The companionship of a dog is also a major factor as well as the need to exercise it, and yourself. Guide dogs get blind people out. A spot with it's limited battery would do the opposite.
And finally 90min is pushing it, unless it can lie down and save power in the cafe.
Fun fact: labradoodles were originally developed to be hypo-allergenic guide dogs (they shed in a limited fashion) but the hyperactivity and ADHD of the breed kyboshed that idea.
They train the guide dogs around here, they are part of the normal furniture so much we all assume the person with the guide dog can see. I know labradoodles as well and, no, just no.