I believe she is testing her limits with you, Children in her age group all do this in regard to sleep, eating, the clothes you want them to wear and what food they want to eat. That is why everyone refers to the terrible two's; this is only because the children do not know the reason why the parents keep on wanting to make decisions for them when they feel they can do better for themselves.
In her case I am sure she does enjoy staying awake until late and does not understand why you would like her to go to
sleep. In her case she will not understand the reason that this will make her tired in the morning, so the solution is to simply establish a routine in the evening and stick with it. Your wife has asked us to reduce her sleeping time here and we will do our best to comply with this request but often children behaviour is different at home no matter what they do at daycare.
To be a parent is not an easy task in my personal life it has helped me to know what is the definition of spoiling a child and what I learned is: "A parent should comply with a child request only if he agrees with and no other reason" but often the love I have for my daughter has made me do things for her that I not always wanted to do.
Please take in consideration that often when children have a growth spurn the children muscles are growing and this causes restlessness. In few weeks everything will return to normality, she might be a bit displeased if you try to make her go to bed at 8:30 but in a long run this will make her feel secure and loved. Try giving her a warm bath and a cup of milk sometimes it helps.