Paris is a lot flatter than Aarhus, which has much higher bicycle usage. And if you need to go to Montmartre, any Decathlon in Paris sells perfectly decent e-bikes for a few hundred Euros. It's infrastructure, not culture or hills or weather.
Yup, it is infrastructure. All those quaint cubic rock paved hilly streets in Montmartre with obstacles tobprevwnt cars parking and and cars parked on the side are a cycling hazard, especially when it rains.