That is a fair point. Although, can you compare this situation to other businesses where the treatments towards the workers are more fair? For example, I invest in real estate partnerships (syndications) where the sponsor does all the work (i.e. puts in time) and investors provide the capital to the sponsor to buy the deal and execute. in 100% of the cases, upon liquidation investors receive all their money back plus a preferred return (usually enough to make a 5-10% IRR). After that, if anything is left, the profits are split between sponsors and investors depending on the agreement. The sponsors also get a monthly fee (usually a % of the gross monthly revenues) to justify their time investment. In this case, the situation is quite similar to a startup, where employees get a monthly salary and have the option to participate in the upside, if they execute well. These kind of arrangements are quite customary in all industries where private equity is a way to bring capital.
> Advantage relative to what?
I interpreted your original statement as if you were implying that the strike price of the common options is typically equal to the current price of the preferred shares (quote: "the company may justify the strike price based on the valuation of the company at the last funding round"), and I was pointing out that's not the case, so the pricing has a slight advantage with respect to the price of the preferred shares, so if the company were to be sold today at the exact last round valuation (e.g. X), the employees would still net X - Y per every option they have (where Y is the strike price), as opposed to 0, even if those options were granted while the company had the same exact valuation. Maybe I just misinterpreted.
Of course it would definitely be better if startups granted shares rather than options, but I am not aware of any company at early-medium stages doing that.