Aren't most developers in the world paid a salary or day rate and thus are paid for their time? What incentive is there for them to "hurry up" rather than sandbag?
There's a minimum quality level required to not get fired, and I wouldn't be surprised if that's exactly what most employees deliver.
Personally, I would just optimize stuff or propose new features for a product if I would learn something/gain experience out of it.
Stocks are too far away from the actual software. The CEOs stupid pet project might well ruin the company's financials, even though all of the engineers on the core team did a fantastic and highly profitable job.
So stocks are more bets on the CEOs performance than on the engineers'.