Hackers hit supermarket freezers in seven European countries. How exposed is everything else?

A cyber-attack took out shop freezers in seven European countries and the UK meat industry, and some stores had to throw away piles of food. It's a reminder that a lot of everyday equipment is now online, often with weak security. If freezers can be hit, what about building heating, elevators or hospital equipment? Who should be responsible for securing this stuff, the makers or the shops?