The actual problem is production. Airlines don't want to buy the MAX. The issue is is, if you want to order 100 A320s or 100 A220, you are gone wait a long, long time.
So you have two options, no planes, or the 737 MAX. Those are their options.
So you have two options, no planes, or the 737 MAX. Those are their options.
[1] https://en.m.wikipedia.org/wiki/List_of_Boeing_737_MAX_order...
[2] https://en.m.wikipedia.org/wiki/List_of_Airbus_A320neo_famil...
Since the MAX initial problems the A320/A220 have been growing far more orders is pulling ahead of the 737 by quite a bit.
And to compete on price, supply chains become more specialized and more fragile and efficient, or software is added to reduce pilot training fees.