Amazon have a total of 1800 Mercedes e-Vito vans ordered to service the whole of Europe presently, with 500 destined to come to the UK. So that's 1800 vans to service close to 750,000,000 people in Europe and 500 to service 65,000,000 in the UK. We are truly blessed.
Unfortunately, how the courier industry is set up, the cost in most instances is handed over to the contractor doing the "last mile" delivery. In other words Amazon, DHL, TNT etc sub contract the most expensive part of the delivey/collection process to third party suppliers who choose what vehicles to put on the roads with many variables to factor in. The high price of an electric van, even when reduced running costs are factored in means that most contractors won't be looking at anything but diesel vans for another decade at least IMO.
I've been crunching the numbers for supplying my local Amazon depot with EV's and the return on investment is negligible tbh. They aren't noted for being the best payers out there.
Looks like we'll be sticking to e-cargobikes for the foreseeable future, supplemented by diesel or Nissan E-NV200 sized vans to cover 70% of capacity.