As you see I was careful to say "could lose", and gave a worst case situation with some cheap batteries. That is far from the case with the best high end batteries, which if cared for suffer very small loss over two years.
In addition a few batteries like the Panasonic ones for their crank unit and the Kalkhoff-BMZ batteries have a sleep mode which cuts in after about two weeks unused, further reducing capacity loss with age.
On the basis that an e-bike supplier would be unlikely to tie up money in more than three months or so of consumable stock, there's nothing to worry the buyer.
But of course my advice still applies that one shouldn't buy a battery to save it unused for a couple of years or more, since it's just paying for such loss as does occur with money that could be earning interest in a savings account for two or more years. Plus there's the nuisance of charging every three months or so to maintain good condition.
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