In fact it is specifically written to be a judgement call:
"At the discretion of the on-ice officials, should a substituting player come onto the ice before his teammate is within the five foot (5’) limit of the players’ bench (and therefore clearly causing his team to have too many players on the ice), then a bench minor penalty may be assessed."
If the other player is clearly coming straight off, and is not in any way involved in the play, and the puck is no where near the bench, refs generally are just not going to call this. Maybe they might if you are trying to make a change out of a bad man down situation, or stuck in your own zone situation, but this was pretty benign. The only reason Colorado scored was because TB was stuck in their own end for so darn long their defense was completely wiped and basically just let Kadri waltz by.