A lorry is also not strictly necessary if you have a Smart or a wheelbarrow. There is plenty of use cases that are only reasonable thanks to having a bike. I for example went to work by a combination of bike and public transport. Car alone would have been 1h, public transport and walking as well, but bike and public transport was 45 min. (Car and public transport did not work together for lack of parking) By your logic, the bike was unnecessary and that is true but beside the point for the sake of 2*15min a day.
Just because most people are doing something does not mean its sensible. Most people are also overweight, even though everyone knows that that is not healthy.
Yes there are cases when a bike will be faster, because your destination happens to be poorly covered by public transport, but on average it's not, and that's what's really important.
Just because most people are doing something does not mean its sensible. Most people are also overweight, even though everyone knows that that is not healthy.