I think the author realises this is not a real life problem.
Although I understand the danger of over simplifying things to the user, I don't think it is necessary to make the user aware of the specific HTML element they are interacting with.
Yup. No need to explain the phylosophical (read: technical) difference to mom. In her case, both types of buttons, as well as links, just take her "to the next page".
What happens to data in the background ultimately doesn't matter.
Remember that a button, like in real life, only means "press here and something will happen".
Nothing more, nothing less.
I don't know if I'm dumb or something but what is the problem ? For the user I mean. He knows that if he clicks, something will happen, maybe it will take him somewhere else and that's all, isn't it ?
Furthermore, I'm not sure every user has the reflex of opening every link in a new tab. Because I understand the problem is mainly in this ? If it is, I don't think the problem is the design but the name of the button, mainly.