I realise there has been a shortage for years, but something has tipped the balance in the last few months and the people I speak to in the Food Manufacturing industry where I work all say the 20% that has tipped this over the edge and led to the empty shelves is Brexit. The recent gas issues haven't helped for some of the firms I work with, but the empty shelves were happening before that.
I get there's been an issue for years, but to go from full shelves with some clever logistical planning to empty isles in a few months is not a coincidence.
As
@Sparky_Hughes says, conditions for drivers are appalling too, so if we really want to replace drivers with UK workers we're all (rightly) going to have to pay for the wage and condition improvements.