this is actually not new, when the hydrogen cell batteries first came out they had to have a certified tech on hydrogen cell tech to work on them, nobody else was allowed. Now with these new lithium batteries and possibly sodium they are installing electronics on them which would require training as well. The mfg would require the certified tech and it would be up to the dealer to make sure their tech's were trained.
And to be honest, back in the day we used to do our own battery repairs then if we knew how, otherwise we called the battery company to do it.
Today tech's are very picky about what they want to work on unlike a couple decades ago when most tech's i knew were cross-trained.
and what dexter said is true, the mfg is just paying to put their name on them, they are still built by the main battery mfg's in most cases.