The pesky "Ordinary Effort" comes in here. Rule 10.13 ....An error will be charged for each misplay (fumble, muff or wild throw) that prolongs the time at bat of a batter, that prolongs the life of a runner......Add to that from comment 2 of the rule: ....in the scorer's judgement the fielder could have handled the ball with ordinary effort.....
For practical purposes I agree with CabbageDad's approach to these plays. If it is a clean one hopper in the knee to chest area then there can be an E. It would be unusual to charge the error on these plays though. It would have to be a real good throw and a really clear play that the catcher basically butchered. IMO if the runner is 15 feet+/- from the plate or closer (or about 2 strides) when the ball reaches the catcher - no error. If he kicks a good throw with a runner 30 feet up the line...then I can see hanging an E on him.
Another angle on this play is the failure to stop the throw where a stopped runner then scores. Now you have to give an error to someone. It then becomes the judgement of the scorer if the throw was wild or if the catcher should have stopped it. For any throw that bounces, that error is going to the guy who threw the ball with the exception being if the base was left uncovered by a defender that should have been there. For example a throw that goes into CF on a SB when neither 2B or SS cover the bag.