It seems that lately I've come across an unusual number of companies using very old, customized accounting and inventory management software - mostly dating back to before we started using the term "ERP Software".
These companies are still using the same software, sometimes 20 years older (or older), because it was customized for them back then, they are accustomed to how it works and what it does, and they've not found any current software that works the same way. And they are loath to customize any new software system, because that's what got them into this situation in the first place - once customized, their old software could not be upgraded to a newer version.
A reality check will tell them that, aside from the customized features they rely on, they are losing so much in terms of productivity and efficiency by clinging to 20-year-old software, developed before many now commonplace features existed - such as emailing documents and reports, workflow automation and access to all kinds of information in real time.
And some modern accounting and business software packages are now customizable with full upgradeability. So why would a business owner persist in using an ancient system, which is probably supported (if at all) by one very part-time person? If you figure it out, please let me know.