Why do scrambled/fried eggs stick less when cooked with butter instead of oil? Whenever I'm doing scrambled or fried eggs, I use butter and a regular frying pan (aluminium I think) without any special non-stick coating. They never stick to the pan, it's as if they're floating on top of the butter within the pan.

My wife usually uses oil, and whatever she does, the eggs always stick in the pan, and it's a pain to get them out, and fried eggs usually become a broken mess.

So, why would cooking eggs with oil make them stick to the pan, and doing it with butter wouldn't?
Technique is the key here. If she is using oil expect she is adding the eggs before the oil is hot, she is probably also rushing her attempt to turn/flip/scramble/move them. One of the hardest things to learn when frying eggs is to walk away immediately after adding the eggs to the hot pan.
I notice you are in Germany, I don't know what your access to the USA's &quot;Food Network&quot; is but this episode of a Alton Brown's &quot;Good Eats&quot; can show your wife &quot;eggsellent&quot; technique.
(pardon the pun, couldn't resist...)
New Links:
Good Eats: https://www.youtube.com/watch?v=Fx8up7UJv2s
Alton Brown on CBS Morning Show: https://www.youtube.com/watch?v=pD3QeyK4bJY