I came across an article this morning about the rife practice, in the airline industry, of selling fundamental features like communication, navigation, or safety systems as “add-ons”: expensive optionals that are therefore given up by those airlines that make of the word “low-cost” their business.
This is the case of Lion Air, which regretfully experienced (in October 2018) the crash of one Boeing 737 MAX, allegedly due to a “malfunction” of the MCAS system, supposed to stabilise the aircraft (pitching the nose down) if conditions are those that a too high angle of attack is sensed by the AOA sensor(s).

What allegedly happened is that a false angle of attack reading from the AOA, prompted the MCAS to move up the horizontal stabiliser in order to pitch down the aircraft nose.

According to the information that have been shared with the public, the second crash of a B737 MAX, occurred in Ethiopia in March 2019 (Ethiopian Airlines) is related to the same issue. Perhaps they found the stabiliser jack-screw set at its upper end (see picture above).

Now what came out is that what I suppose to be a couple of very important features, where missing in both the crashed 737MAX.
Indeed, the optional “angle of attack indicator”, which displays the readings of the two sensors that determine whether the plane’s nose is pointing up or down, relative to oncoming air, was not installed because it was not selected among the “optionals”.
Furthermore, the optional “disagree light”, which turns on if the AOA sensors contradict each other, was also missing in the cockpit of both the doomed aircraft.

While can be easily understood why many airlines decide not to buy them, I have some difficulty to understand why do not the regulators require such features that are obviously significant on a safety point of view.

Wait a moment… should not be the Authority that one working for the sake of the citizens safety? Why the FAA did not mandate to Boeing the “angle of attack indicator” and the “disagree light”?

Did they help them to deliver a cheaper product? which can be sold more easily out?
Did the FAA provide some special facilitation to Boeing, facing hard competition with the Airbus A320 Neo?
Did the FAA loosen up a bit too much, for the sake of the national industry business?

Are those above written, legitimate doubts?