From outside your own household you can still potentially 'gather' with one other person. I can go out and meet person a) later on meet person b) and later on down the road person c). Thereby sending the virus on it's way to who knows how many other people? Yes I know we should be at least 2 metres apart but unless you've got a measure stick with you people aren't going to observe this.
Is there something I'm missing cos it's not making sense as a proper lockdown.