Lots of reasons and possible reasons:
Shopping. The 2m distance thing is no guarantee of safety,, going into a shop where people have been breathing all day.
Work: so many key workers still in contact with plenty of people, at work and on transport getting to work
Idiots not understanding and /or flouting the rules and putting themselves and others at risk
The exponential rise in infection - the people infected up to 3 weeks ago will now be ill...but the people they unwittingly infected will be falling ill in even greater numbers.
Airports.
Accidental transgressions of rules - people in my local park clearly have no real understanding as to how bug a distance 2m, is. People stand on either side of a path, at a distance, having a chat, and everyone else has to stop or walk between them - why don't they stand long the path rather than across it?
Cyclists and runners leaving slipstreams of aerosolised virus particles as they breathe hard and are not always 2m apart.
Kids,, maybe asymptomatic, but touching things in shops and out and about as kids naturally do
Kids still in childcare settings for key workers.
It is a lot to stop, at this stage.