I know of a restaurant franchisee with 170+ locations that uses a home grown ERP system built in VBA on top of Access by an accountant about 20 years ago.
I once had to update it to optimize (minimize) front-line staff working hours so the company didn't have to pay health insurance for those employees. A real nightmare of a task in more ways than one!
My first programming job in the 90s while I was still in college was building systems exactly like you describe (and they were as poorly built as you think hah). I worked for a small IT programming/consulting shop. We did small jobs like this in town in addition to installing networks, IVRs, etc... while working on larger software to sell (which is an entirely different/crazy story that involved burning CD demos and using a hand 'stomper' to label and then mail them out).
In high school I got a gig rebuilding a pre 2000 Access DB + VBA front end in office 2003ish due to some kind of incompatibility that was preventing them from upgrading their PC's.
It was a chemical safety database. It was used to identify chemical risks and track the storage of the chemicals.
I pray near daily that someone else came along years later and rebuilt it in a modern language.
One of our clients runs everything on access; from the office security, factory automation, ERP, crm, hrm, cms and more. We are moving them to a cloud platform that will allow them to not change one thing but save them a fortune not having to deal with the many issues access has.
I once had to update it to optimize (minimize) front-line staff working hours so the company didn't have to pay health insurance for those employees. A real nightmare of a task in more ways than one!