Incredibly stupid decision to respond this way by Wag. How bad to you have to be at PR to screw this up? It's not hard. Liability in the case of harmed pets is extremely limited, so you just pay it all and apologize profusely. There's no way the bad press will be worth saving a couple thousand maximum. Absolute idiots.
Missing from the discussion as far as I can see is mention of the walker’s behaviour. I don’t know what rules Wag have, but calling the owner as soon as possible and stating what has happened is a pretty basic thing to do. Deliver the bad news to those that need it as quickly and accurately as you can, with updates when appropriate. Not answering then lying is not ok, and whatever Wags’s rules are this shouldn’t have…
I can see a dog being excited, put with other dogs he doesn't know very well, and one dog breaking loose... running into the street while the walker holds on to the other 3 they are walking... total shit show. You want a consistent dog walker, you want someone who will put time in to get to know your dog, and you never want unfamiliar dogs around your dog unless it's properly supervised.
The whole situation, in my opinion, is prone to disastrous outcomes. Can you imagine if AirBnB booked multiple families to a site at a time? We'd all flip out. But it's OK for our dogs... likely because when we're at work we don't know what goes on, out of site, out of mind.