If it is electronic (in a computer) it is not secure, to easy to duplicate and move someplace else. If computer is connected to the internet, it's over. This is why stuff that matters is not done on systems that connect to anything. Thus why defense systems, secret/classified data, and things of that nature don't connect to the internet, they instead use things like CD roms, and even floppys to move data around. Hard to hack/steal stuff when you need to gain physical access to it, and put yourself at risk.
Your Dr's office, medical stuff is in no way secure, those are among the least secure systems out there. Your doctor is a doctor, the person manning the phones is not an IT tech. The lack of a proper federal system where all data goes is the problem. It's the the rare place where a big database is needed. Medical offices, hospitals have near no IT/security on your data. This is why you do everything you can to prevent them from having it. Even worse is they have decades of bad ideas and mis-understanding. Look how many have "forms" and want things like your Social Security number, not only do they have no reason for it, they can't go asking for it, but many demand it (never give it to them). Many will swear they need to make a copy of your drivers license, that too is illegal and based on a mis-understanding of a law, even after congress and the supreme court clarified both they do not need to make copies, it's also against the law, they still do it. That said, the one small bit of hope is they do understand not sharing it, not giving it out, not selling it. But the issue remains their systems are famously in-secure.
Again, soon as anything is online in a computer, it has no security. Beyond that your are basically dependent on what people are going to target. A lot of places simply are not on the radar of anyone looking for info, so luck can be on your side. Amazon is a target, as are all big companies. They harvest, mine and curate massive databases on you, it makes them a huge target. Plus they are the ones using it for bad. Amazon doesn't need to be hacked to do you harm. Also you don't have to be involved with a company for them to have stuff on you and put you at risk. People saw this with the credit reporting hack. Those who have never done anything associated with that reporting company had files because they had created one of you anyway. Or facebook, they have files on you, even if you have never had a facebook account or any involvement with facebook.
Never trust anyone with your information. Amazon makes money based on data on you. They are "hacked" by design. Most e-retailers learned long ago, people don't want accounts, logins, etc. They aren't needed, just like you don't have those things at the corner store. Let people make a purchase with as minimal information as possible. Amazon is one of the few retailers left that demand you create an account.
The US desperately needs to catch up to the EU, on this. But it's still a battle that is unclear if it can be one. Amazon and others can/could blackmail everyone in congress, so good luck expecting change there.
At least a large chunk of the population has had enough. Retailers in New Jersey were trying to eliminate cash sales, the state came back and passed a law requiring they take cash. Retailers had no ground to stand on since use of cash for payment is on the rise. Folks have had enough, data breeches did a lot for this. While I'm not full cash, there are retailers now I only use cash with, they showed they can't be remotely trusted.