You NEVER get what you pay for, or the person selling it to you won't be in business long because they're not generating a profit. You always get, and should expect to get, somewhat less than what you paid for!
Engineers should not offer their services for free to for-profit enterprises, whether they're offering those services for free as a student in a free internship or as substantial uncompensated overtime. Engineering services are of value, and offering them for free to those who would profit from their use, de-values those services. Compensation can vary in nature and quantity, but when it's ZERO, we're all in trouble. At least these "borrow an engineer" kids are attempting to obtain some compensation for their work- and you can't fault them for being creative in the way they're going about it.
I feel the greatest sympathy for the LARGE FRACTION of engineering grads who currently cannot get a foot in the door in their chosen profession. I'd fix that problem if I could- by reducing the number of engineering grads entering the labour market to more closely match the labour market demand for their services. Given that we subsidize tuition substantially here in Canada, that is the most sensible course of action for our society as a whole- cranking out three times as many engineers as the labour market could possibly use is an idiotic strategy. But I won't collude in making their situation worse for my own profit by accepting their services for free, whether formally as interns or informally through a cut-rate "borrow an engineer" gig economy service model. That stand of valuing the services of other engineers is consistent with the professional engineering code of ethics I affirmed when I accepted my license.