There has been an increasing emphasis on preventive cardiology as described in the following article:
https://www.acc.org/latest-in-cardiology/articles/2019/10/10/23/20/the-future-of-preventive-cardiology-training
There is even an entire medical society dedicated to preventive cardiology:
https://www.aspconline.org/
Finances money costs. Long ago with my then cardiologist he went with retirement some years ago, I ask why they do not do population tests his answer was they would find too many patients needing something done.Is a lot of undiagnosed people out there.Not all issues of heart give symptoms or mild symptoms are taken for something else. Mind you when I went to cardiology first time was for a simple thing, BP meds my GP prescribed was not working at all. My GP switched my meds several times before I got a ref note to be allowed to go to a cardiologist. I am in EU and rule here is first you visit GP and they decide if and when a specialist is needed. Once one is with a cardiologist depends on what one has, they sort of can do certain things/tests/meds/therapies/gadgets like pacemakers etc. When my cardiologist went with retirement was only 5 people left of the ones when he had just started his practise.Over the decades I have seen many faces in that waiting room.
The truth about cardiology might take a book the answers are not easy. My second cardiologist who I have now had a few years I see him once a year, few tests and home I go, and here I am answering this.