Can someone explain what's up with the tipping culture in America?

Alright, I don’t actually get it. Why on earth does there have to be such a huge reliance from hospitality staff on tips. Surely it isn’t difficult to pay someone a liveable wage?
Being Australian, I’ve never tipped more than $10 for anything, it’s usually a max of $5 if the staff and food was nice. Sure, it’s a bit more expensive, but it means that people are actually able to live…

I don’t want any attacking or anything of the sort in here, polite debate is fine, I’d love to hear the opinions from both ‘sides’ (if that’s what you call it).
Why does American hospitality cling to the tipping culture?