Same here. We live 18km from the city center. We have an electric car that we rarely use and two e-bikes (45km/hour kind) that we both use daily to go to work (300m elevation change). It's perfect !

How long do your batteries lasts which such a workload?

I have a short 15 minute 3-km ebike daily commute. But after 1 year the battery is obviously weaker. And i never made it past 2 years before a battery swap. I charge daily.

(I still kept my smallish car, which i now use much less)

My ebike has a 814Wh battery. It'll easily do to and from work twice. I've already done 7000km with it and no noticeable difference (<10% ?). But it's true that the battery degrades. I don't really "mind" in the sense that I treat it as a consumable and not a forever item.

That seems particularly poor. I'm still doing regular 30 mile rides with plenty of reserve after 6,000 miles on my original 500 wH battery.