You can get a Prius battery with BRAND NEW cells for $2K:
https://www.greentecauto.com/hybrid...rius-hybrid-battery-with-new-generation-cells
Meanwhile, take my 2015 Volt for example... there are no new cells available. There is nothing to rebuild unless you just want to mix-and-match used cells. Even though its 17Kwh total/10Kwh usable pack is small compared to most "real" EVs, the lack of availability of new cells is the bigger problem.
Long term rebuilding will never work out unless new cells are available. And vehicle manufacturers have no incentive to make new cells available for past EVs.
What I'm trying to say is you can't compare the low cost and ease of replacing a battery in a Prius to doing battery work in literally any actual EV.