I think you'd be surprised at what goes into running a dealership. The software is complex with a lot of dependencies.
You have a full parts/warehouse inventory system and invoicing internally and to other mechanics. A service system (including rosters and timesheets) and it's own invoicing system to customers. You need a vehicle module to manage all the local laws and taxes as well as interfacing with manufacturer systems for models and options (which are God awful undocumented weird binary formats over long dead networks - sometimes hardwired through parts of the phone companies that even they don't know they have anymore) so you can sell to customers.
So that's 3 different invoicing systems to start. It all needs to be underpinned with an extremely flexible accounting system in the back end because every dealer does stuff differently but all of those things are related. The parts department sells to the service department at a discount; the service department prepares new vehicles for sale (called pre-delivery) and bonuses and rebates occur through each step.
You need to import a lot more data covering log book service information and parts catalogs. And lots of reports for those car companies and online sellers and more.
Some of that isn't exactly a programmers problem but the breadth of the issue and lack of generalised knowledge sources (and how every car manufacturer does things completely differently), it's a minefield to keep one going let alone building a new one.
Consequently most of the world runs on only 2 or 3 systems and they're all ancient and generally the companies that develop them are awful and treat customers like garbage. There's a lot of vendor lock in and manufacturers fighting each other.
Car dealerships have a tough job. Also their accountants are near God level skills wise.
Anyway I don't think I answered your question. Yes I also don't know exactly what happened but yeah it was a disaster that only happened to work out because of millions of dollars. Once it WAS ready though money started flowing in because dealers are desperate to get away from the existing awful vendors. On the other hand each wanted so much custom functionality that it led to work pipelines planned years in advance by the time I left - and that doesn't make for happy customers either.
