I have a partner who's a nurse practitioner in primary care and I just want to emphasize how hellish it is for people on the inside as well. The economic model of running a healthcare business is entirely based on their ability to bill for provider time. Healthcare providers have very high costs to match their very high fees and also pay a bunch of people to 'help' providers see more patients. A big part of this mix is also that it is not enough to provide healthcare - you are actually paid for providing documentation that you carried out the specific care that you "should have done" given the case notes. Ensuring you properly annotate the files of patients (for the benefit of generating the right charge codes! Nothing to do with patient care) is another burden that's required to sustainably provide care. As a result the costs "per provider" are much higher than the provider themselves - you also need medical assistants who do every piece of work the provider isn't legally required to do, billing staff to properly bill that work, admin staff to manage their schedule in detail, etc.

The lack of regard for patient schedules is a direct result of how insanely packed the schedules of providers are. Fifteen minutes per patient is luxurious and my partner spends a lot of time after work entering notes for patients she saw that day (she "works" 32 hours / 4 days a week, which is really closer to 40-45 all told). My understanding is that the clinic does not have a high profit margin (serving medical / medicare patients + high overall costs), so every patient counts, and the admin staff will add people w/o permission. It's common for her to find patients scheduled over her breaks or for her to be scheduled after she should have left the building. Burnout has always been bad but it's reaching epidemic levels now in the wake of covid, which further restricts the supply of healthcare and makes people wait longer to be seen.