And the answer is "you have a shitty business model and this should have killed it years ago"
For a dog-walking app (or many others, such as say house-cleaning) - you want an introduction to people locally, repetitively. Once you're happy with what you got through the app, you don't want the app.
Maybe what "Wags" should focus on is the broader scope of "I want a local tradesman to do something repetitively".
Provide introductions, take a nominal fee, allow end-user to change if they're unhappy (and take a very low fee for all the happy people)
To take the Uber model - you are going to take n trips, in m cities, for y duration. Uber and their users want unlimited drivers, riders, cities piled into their app.
Wag is completely different. Your dog is in your home. It needs walking say once a day. I'd have thought the user would want the same reliable person doing it each day - and the walker would ideally want to build a stable of local dogs that need walking each day. Once both sides are happy and stable, you don't need the app.
Since their solution is to sue their customers and affiliates in increments of $1,000, sounds like a pretty dumb business model.
Errm. You'd be surprised. Let's just leave it at that.