That is a topic near and dear to me as an engineer and former software dev (more years ago than I will confess) who has run a solo medical practice for almost 30 years.
There are a few reasons which result in this.
First, systems in a doctor’s office need to work with a diverse group of patients. You might be surprised how many patients are technology averse or even illiterate or have no access to internet at home so are are still unfamiliar using the web. Combining both digital and paper options is possible but can also get cumbersome.
Second, the time to achieve a return of money spent on software can be substantial and the cost to transition systems can be even more substantial. For a small practice it can be most efficient to have paper as a primary means of collecting data from patients; the advantages of a digital system come mostly to large practices. And while there are “free” cloud-based offerings, the doc cannot necessarily count on those staying free forever and there can be a very real cost exporting such digitally siloed data into another system in the future.
Third and most notable by far - there are very important rules on protection of privacy which are required in medicine for both legal and moral reasons. Particularly for docs who are not highly tech savvy, it is not as simple as buying off-shelf consumer software and installing it in their office; it may be necessary either to work only with softare vendors who sell HIPAA-compliant versions of software or to hire a consultant to assure the office IT systems are HIPAA compliant.
A related issue is the extreme importance of being sure no digital records are lost and thus how to set up a totally bulletproof backup system while at the same time not violating patient privacy. This may not be a big deal for a doc who is a techie but can take quite a bit of money (with minimal ROI) for docs who have to outsource this to a consultant.