Mobs hitting through blocks

Mobs can hit through blocks i can make a square and sit in a corner after a zombie or spider see me and trap myself inside but ill still take damage which is the fast way to tell
1.First time is was a spider that hit when was in a 1x2 dirt house (inside area)
2.This time in the picture below a baby zombie on a pig could hit me while i was on that dirt which the ground dirt was the same on the outside and inside other then i was 1 dirt higher
p.s I checked and the only thing I seen was a old post about the MC java version but most are from 2013-2012 issue