You have to get the baby to open his/her mouth and put it around the breast, bringing the nipple up to the roof of their mouth. That part might be intuitive.
Then you have to get them to form a tight seal with their mouth. They're definitely not great at this.
Then you have to get them to do both of the previous steps at the same time while also sucking hard and not breaking the seal. People make entire lifetime careers out of being "lactation consultants" to help parents train their babies to do this properly.
Then there are the extra problems that aren't directly related to sucking that interfere with eating. For example, our baby would fall asleep within five minutes of starting to eat, he was so relaxed. The pediatrician got us to escalate attempts at keeping him awake until we were literally holding ice cubes against his feet to keep him awake while eating, which is about the only level of stimulus that would stop him going to sleep.
He's getting the hang of it now, though. But it took two months of training around eight times a day, which probably isn't going to meet anyone's definition of an intuitive interface.