It cannot be assumed that the creators of ransomware will not try to cross the line, if a consumer's computer is fair game, which can cause all sorts of problems, for example, loss of an important degree thesis, the inability to pay their bills (heating bill in a very cold state/province) or the ability to conduct normal day-to-day commerce, etc., it all results in a loss to the consumer and economy as a whole. Hence, their cars and medical devices might also be viewed as fair game by the creators of such, harmful software.
Maybe, there are few build-in mechanics in the technology market that keeps a consumer safe, for instance, multiple devices should translate into data residing in multiple place. However, the user should follow best practices, for example, don't click on unknown sites, have good antivirus software and keep it up-to-date, etc.
As for businesses, they have to enable greater measures, because if a consumer's car is not starting then, it's not the consumers problem, the business has to fix it. In which case, I guess that prevention will cost less then, the cure for the business.