Why is “Enterprise” software terrible?

The term “enterprise software” mostly covers software designed for use within large companies. This type of software often has many users and complex calculations for calculating pension statements or bank information. I have some experience with these types of systems. The quality of this type of software ranges from abominable to lean and mean. The quality is unfortunately most of the time more of the abominable type than the latter. Why is that? Are we an industry for the larger part completely incompetent? Are we not able to deliver a working piece of software that matches all functional and non-functional requirements? I do not think that this is the case. I’ve seen too many very good coders write utter junk because of time pressure.  I noticed while browsing the following post, in short: “The buyers are not the users”. I think this make perfect sense. Add to the fact that when buying software we try to spend as less as possible and you have the perfect recipe for a useless piece of software. The future? Much more reuse of common components using Open-Source Software. But were not there yet unfortunately.