"All" of them are not, Leon.
From what I have read, around 2-3 per 100,000 ICE vehicles spontaneously combust. For electrics the figure is 4-5 per 100,000, so " over 100% more" in media talk.
That is the crux of the matter - media representation. Far more "newsworthy" to post a picture / video of a burning £75K electric car than a cheap petrol vehicle.
Exploding e-bike stories often have (buried deep in the text, almost as an afterthought) a comment from the fire authorities of the items concerned being "bought off the internet, being charged with incompatible chargers". I have not heard widespread suggestions (or any suggestions actually) that, say, Bosch e-bike batteries, correctly charged with Bosch chargers, are a problem.