You’re down playing the social and anchoring forces. For instance, you’re in a long line and you’re prompted to pay, the no tip or tip less than the default options is always more difficult. These default options are used by employers as a way to under pay staff. If these default options were made clear before the purchase there would be a pressure for businesses to reduce or remove those options. As it stands, the default options is a strong anchor.
It’s deliberately more difficult to not tip, it’s always more buttons and less obvious. Ideally tipping should be abolished (with employees being paid a decent wage) but until then, some form of regulation would be helpful. Otherwise there is no pressure for businesses to act better. I still think my suggestion fits into the theme of this thread.