There are a lot of places where manual labor is preferred to automation, not because automation is hard, but because automation is expensive, while labor can be found for dirt cheep.
Order picking is, in the grand scheme of human employment, essentially unskilled labor. It takes a bit of practice to get efficient, and a certain level of perseverance and endurance to operate at top efficiency, but it doesn't take any form of higher study, credentialing or apprenticeship to become qualified at. Scaling seasonal workers in this role is relatively trivial in terms of expense compared to purchasing robots.
Final note: humans take years to become obsolete and replaced by newer generations. The same isn't true with robots. If you can get full use out of one year round, it is much easier to justify investing now rather than 5 years from now than if you only get two months a year use out of it.
The cost of living is not just related to salary but also energy being 3x more expensive than usual, house prices, food prices going up 30%, Brexit, etc.
Any increase in wages is taken by landlords who increase the rent. The competition for a house isn't the next door house, it's not living in the city at all.