the virus does not discriminate
Well, it does actually. Not everyone gets it. Many who get it don't get any symptoms. Of those that do they now think it has a 0.3-0.7% death rate. Most people (by far) who get it will survive it. There is space in the hospitals for those who will sadly end up needing it. Anyone particularly at risk can take the decision not to go and buy plants (hopefully they have someone who can buy plants for them, though, as everyone knows plants are absolutely essential to well-being)
And surprisingly, many over 70's are perfectly intelligent so can make their own risk assessment about shopping. They can keep their distance from other shoppers and wash their hands when they get in. 'Lockdown fatigue' can encompass anything from being a bit bored to being horribly suicidal so fair enough if many have had enough.
Garden centres very badly need to start selling their plants. It's like the Christmas season for them.