Lol... I remember in the days of red and blue that you'd loose half of your money from a full party faint. That seems a bit cruel... Though it teaches you to have a decent party. It would almost seem that staying at a Pokemon centre is free, and perhaps the kitchens are hostle like, where people can take what they need. Though there is a reception area for trainers checking in.
But what I think it really just is, is that they have unlimited funds, without much explanation, just because it is easier that way. This allows those who create the anime to do whatever they want with their characters, while never having to directly answer the question.
Or:
....Damn.
I was just scrolling down this thread just to post the very same picture, and you had to beat me to it.
..Damn.