More important than "the execs believed all planes have the feature" is that the claim after the Lion Air's crash was that at least these companies which did pay for the "extra" would be able to not fly the dangerous planes, as the technicians would discover that one of AoA vanes is not working while the plane is still on the ground. But that was also a lie (from the NYT article):

"“We were told that if the A.O.A. vane, like on Lion Air, was in a massive difference, we would receive an alert on the ground and therefore not even take off,” said Dennis Tajer, a spokesman for the union representing American Airlines pilots. “That gave us additional confidence in continuing to fly that aircraft.”

But in the last several weeks, Boeing has been saying something different. Mr. Tajer said the company recently told American pilots that the system would not alert pilots about any sensor disagreement until the aircraft is 400 feet above the ground."