As Moobli says, back in the day there was usually someone around at least part of the day. When I was breeding I would never sell a pup to someone who worked full time, even if they had arrangements for a lunchtime visit, as I felt it was setting the pup up to fail on house training etc. I have always worked round my dogs, and the most they have been left is 4 or 5 hours, very occasionally longer. I am thinking of having a pup in the not too distant future and my plan is to only be away for a couple of hours at a time whilst it is young.
The thought of these doggy day care centres fills me with horror, there was one on a local news programme a while ago and it made me cringe, you could just see from the body language of some dogs that they weren't happy.