When the founders still control the board, in practice the buying company understands that what makes the acquisition work is that said founders end up happy, and that the outcomes for your typical employee can be sacrificed to the edge of what the law allows.

Maybe there's management carve-outs. Maybe the total value of the acquisition is lower, but as part of the negotiation, there are great transaction bonuses, or retention bonuses. The investors with preferred shares still get their liquidation preferences, but the common stock is worth a pittance. Maybe instead of an acquisition, some of this is turned into an asset sale, or there's some considerations for founders that involve very friendly rollover equity. Maybe the founders add a new kind of stock, or create a new legal entity as part of the acquisition that does... "interesting" things. An inventive legal team cannot do miracles, can make sure that the employees feel robbed either way.

The acquirer, the founders and the VCs with the biggest share will get what they want, and come up with something neither will challenge. So it can be down to just the workers to pool together and decide to sue for violation of fiduciary duty, which might not be fast or easy to prove. You aren't in the room where it happens, but everyone else is.