I cannot agree with this at all. Verizon clearly spends a lot on infrastructure - they have the best 3G coverage, and best LTE coverage, than anybody else in the US. LTE is very, very new and seems to be rolled out faster on VZW than VZW rolled out EVDO/3G ten years ago or so.
If there is a company that seems to have squandered their network, it is AT&T. Have we all forgotten how terrible AT&T has been in major cities since the iPhone was released (particularly the 3G)? I guess that things are better for them, finally, but it sure took a long time.
This article is a couple of years old: Verizon Leads Att By Billions In Infrastructure Spending - Companies & Execs - Portfolio.com
but this one is relatively new, and talks about massive investment in infrastructure by VZW in California: Verizon Wireless invested around $730 million in California | BroadbandExpert
I think that the explanation of providing workshop services, etc., is a smokescreen. I think the truth is that LTE expansion is expensive, the market is becoming both more competitive (so pricing cannot be easily raised) and there is more data being used and fewer talk minutes, and the data is more expensive to service but a smaller monthly revenue for the carriers. The upgrade fee is a way to raise prices without making it look like you are raising prices, and it amounts to about $1.50 a month over the life of the contract (assuming most people upgrade smartphones as soon as they can - every 20 months.)