The MCAS wasn’t an issue of cheaping out, it was an evolution of a less-dangerous system that fell through the cracks and highlighted shortcomings with the FAA’s self-approval system. It’s a long story, but the short version is because the type of system it was wasn’t considered critical it was approved for being fed by only one source of data. And in its earlier iterations for military use it was far less powerful in terms of how much stabilizer trim it could apply. As it evolved it became much more potent, and also reset every time the pilots used their trim switches, leading to disaster. Mentour Pilot has done some really good videos about it, especially his analyses of the Lion Air crash and the Ethiopian Airlines crash.

Now it receives data from multiple sources and won’t activate if they disagree profoundly. It also can only ever activate once per flight now, which means even in the event of erroneous activation the pilots can easily trim it out.