Two things happened recently. DH and DS aged 4 arrived home in the car and DS got his finger slammed in the car door because he had hand near the door hinge when DH closed it. DH denied responsibility saying DS shouldn't have had his hand there. It's not come up before and it's not something I've had to discuss with him so he might not have realised the danger.
The second occasion was when they went on the bus with a little stuffed toy and it got left behind. DH said it was DS's fault as he should have been looking after it. AIBU to think that DH should look out for him more and not expect a 4 year old to be completely responsible.