I have no experience in this field, but do you think it's more likely they are making crazy profits or that they are just really incompetent? probably a little bit (or a lot) of both I'd imagine.
It can be a combination. Often it honestly depends on both sides of the project.
I've seen projects where bad requirements led to cost overruns and/or delays due to required rework.
I've seen projects where due to bad/strict requirements the customer's product basically became the 'learning platform' for a team to use 'the hot new web ui framework toolchain' of the year. I made sure to completely forget what I 'learned' about react/redux after leaving that gig.
I've also seen projects where the contract house threw bodies on that didn't even know the language used. I've seen horror story houses that are code-genies that overcharge to give you exactly what you didn't want.
But in this case My guess it would be a combination of requirements fustercluckery alongside what sounds like an integration nightmare; from my time working in an environment where we had to do a lot of 'etl loads' from different partners and/or acquisitions, you see a lot of snowflake cases.
