Customer able to buy without shipping address

[beatboxing]

A customer was able to bypass the shipping address step and not pay the shipping fee. How could have this been done? A billing address was given. 

Possible reason: Does it have anything to do with paying with PayPal or ShopPay or GooglePay?

Possible solution: Is there a way to charge someone a standard shipping price for all orders in case a shipping address wasn't given?

My website is: www.pureluxe.at

Thanks