replacing the drive train is not normal maintenance, as would be replacing the battery in an EV.
Replacing the battery is NOT "normal maintenance", and most EV owners will never need to do it. The Prius battery is warrantied for 150k miles, and many people have driven their cars much further than that, with no problems. These are for batteries made years ago. Battery tech has improved a lot recently, and new batteries being made today should have even longer lifetimes. Future batteries will be even better.
There are two factors to battery life, the first is the number of charge cycles and the second is the age of the battery. Over time the battery pack will lose capacity. For Prius owners, this process would be gradual and they likely wouldn't notice right away simply because the Prius is a hybrid.
I'm willing to bet that an analysis of older Prius vehicles would show that the battery pack has much less capacity that it did as it was new. Does this mean that it "needs" to be replaced? With a hybrid, it's less of a concern. What if it was an EV? I'm willing to bet that most owners would be demanding a battery replacement because their range would have dropped dramatically.
In the case of the Prius, the battery is used within a certain power/speed ranges (up to about 15 mph), then it switches to gas. This means that the battery pack is under much less stress than the battery pack on an EV. So, while a Prius might go more than 150K miles without having to replace the battery, most of that will be using the gas engine and not the battery pack. Plus, since the battery pack is only used during certain situations, a loss of capacity would be relatively minor with the exception of lower gas mileage. For an EV, a loss of capacity would be very noticeable as range would decrease by a lot.
Battery tech has not improved that much over the last 20 years. Yes, we now have Lithium batteries with no memory and advanced charging systems, but the amount of energy that a battery holds hasn't improved much. So, why do tablets, laptops, and phones last much longer? For two reasons, the first is that the electronics have become smaller which allows a bigger battery to be fitted in the same case. The second is that we have learned how to improve the energy efficiency of electronic components. Perhaps there will be battery capacity breakthroughs, but so far we have just seen gradual improvements.