My understanding is that it IS common to lie, or else to redirect the conversation from what was made in the last position to what is desired for the new position. Why should it matter? You're being hired to fill a position that's worth x amount of compensation; the primary reason to ask for prior compensation seems to be to to get a "deal" (i.e., rob an employee of potential earnings).
There's no such thing as "worth X amount of compensation".
The way it's supposed to work is that you and your employer (who represents the capital) generate a return from your joint venture.
But the actual return is hard to predict. And there is no fair and obvious way to divvy up the return. So it comes down to negotiation power.
There also may not be any condition where you and the capital agree to join. The capital may have better options to generate a return and you may have better options to get a salary.
There is no shortage of ideas how to distribute profits, and no shortage of arguments which one is "fair" or which one is the best for whatever reason.
This particular scheme means you are paying janitors as much as people who went to school for a decade or more. Some people would not find that equitable and fair. Few academics would find that offer competitive.
And depriving the executives of large salaries also means you are increasing the incentive for corruption. If somebody has the power to squander a billion Dollar, you better pay her more than 100k.
And you forgot to include capital gains, or you included it with expenses. Whoever owns the equity will want some return, otherwise they will invest elsewhere (or not at all).
In my country there are very good statistics provided by the technical unions as to what compensation can be expected by region, technology domain, and seniority. I tend to quote those to set my salary and then argue up if need be.
> they don't trust candidates
...which is a great tell for what kind of relationship you would be starting if you did take the offer.