Presumably, such a used primary battery can be processed by a properly equipped facility to recycle it as a fresh battery which can be sold for an appropriate fee. Hence returning a discharged battery would reduce the purchase price of a fresh one. Such an exchange represents an economic model that has been used successfully for other recyclable products. However, it is somewhat more complex than simply recharging a secondary (rechargeable) battery.
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Thanks @paraglider62 for clarifying the Tesla charging times (so I am not compelled to pile on 
). It’s unfortunate that there is so much misinformation out there.