It's been mentioned below that differences in temperature matter a lot. But there's also the fact that erasing a flash block inherently damages it, progressively reducing its ability to retain data.

So I wonder if there's a tradeoff between longer data retention when powered off (by using higher write and erase voltages) and longer MTBF (by using lower voltages). I could be completely wrong here, but if there is such a tradeoff it would make sense for consumer and enterprise drives to make different choices.