I won't pay on your website
Another big one: expecting local information from international customers.<p>My phone number starts with +49 and is longer than a North American phone number. This prevents me from renting a Bixi bicycle in Montreal. You know who likes to rent bicycles? Tourists like me.<p>In any case my card failed with a generic error, both at the payment booth, and in the mobile app (after working one time).<p>Another one was a stand up paddling booking website. I shouldn’t need a Canadian postal code to rent something (especially 10km from the border) yet here we are. In any case it was impossible to select the field on my phone, so I dropped out. I wonder how much business they lost to this single bug.<p>This sort of stuff happens when you ask for data that you don’t need, and validate it beyond your needs. I fight tooth and nail with colleagues to reduce the size of forms to avoid this sort of friction and bugs.<p>EDIT: oh and IBAN discrimination, which is illegal but happens even on government websites