Today I needed to go to the bank, go shopping, make a social call, pick up packages from two locations. I could have used the bike for the bank but I would have got wet in the rain along with spending more time cleaning up after the ride.
I could not have picked any packages up because they're too big for the bike but suppose I had a cargo bike? Well I would still have got wet and so would my packages, and one of the packages was fragile. So no go there.
And the social visit? Yeah I suppose that could have been do-able, but I'd be a tad sweaty, would need to take the bike into their house (luckily straight into the garden, but still) and then make a mess on their floor with my wet clothes (or I could have waited for the rain to stop which it did a little later on).
Yesterday I had to run a few urgent errands and I could have used the bike, but instead of spending 1h40m on the bike, I got things done in 1 hour using the car.
Yes, the car is more expensive to use, but it's overall cheaper for me because I can get other things done (time is money and all that). The bike is far more enjoyable but usually when the weather is good and it's just easier to keep the bike for leisure.
Commuting is a different matter though when compared to using London Underground but both have their advantages. I still prefer the bike in this case.
EDIT: having said that, if I could do those things by bike, I'd certainly be fitter.