Let's say you are a software company based in country C (company) and offer services to users in country U (users), only over the internet, and having no physical assets in country U. You could imagine Microsoft offering Office 365 to customers in Liechtenstein, for example.

GP's point is that whenever you sell or offer something to users in U, you have to abide by U's laws in doing so - no matter whether you did that all while sitting at your desk in country C.

Whether or not enforcement or liability is realistic is up to the relationship between U and C I guess - my guess is France and Switzerland are on pretty good terms.