Yep, it is!
People will try to justify it from both ends, because it's what they're used to -- owners pretend they couldn't pay a competitive wage and still make a profit, staff assume they'd make less if it were up to owners to pay them, and both will say that the expectation of a tip improves service.
But in reality all of that is probably BS. Bar staff convince guests to fork over enough money to add up to a competitive wage every damn day, so it just can't be true that the public at large wouldn't be willing to pay that much for food/drink + service -- they already do, owners are just guaranteed their cut whether or not the worker gets theirs.
And, for all the harping about tipping acting as an incentive to give good service, in practice you learn quickly that 99% of the time people tip a fixed percentage of their bill when they go out. The decent tipper almost always leaves 20%, the shitty tipper almost always leaves 10% or less, the great tipper always tips more. So, with rare exceptions at the margins, what you make in tips is less a question of how on point you are and more a question of who ended up at your bar/in your section that night.
As a result, staff who are fixated on tips - in my experience, at least - tend to do worse, because they're busy fretting/seething over the shitty table they know they just got sat with, instead of focusing on how to stay on top of things in their entirety. It's the staff who come in and just want to do right by everyone and give damn good service, regardless of individual tips, that end up being your rock-stars. (Like with every other job: People who are committed and give a shit about the work itself do better.)
The real long-and-short of it is that tipping exists in its current form in the U.S. because, when minimum wage laws got put on the books, employers convinced legislators to exempt low-wage, service positions that were disproportionately done by poor and/or black workers. It was a carve-out for management at the expense of economically vulnerable workers that the government could bet no one cared about, and the service industry has been jealously guarding that shitty legacy for decades rather than start to shift over to a business model where they actually pay their labor costs like everyone else.