So when my DC were little my friend and I were both single parents and we often used to take each other’s kids to sort presents from the kids for each other.
I also used to sort the kids presents and cards for their father. Even though I hate him the kids didn’t and it’s about them and them wanting to give him something. Now they are older they do it themselves but I do notice considerably more effort seems to go into me than him and his wife (when they were younger she would sulk if they didn’t get her a bday card and present from their part time job/paper round money 
Their Dad sorted presents for her when they were too young to.
Now I am a step mum I am taking my DSDs out later to get a present for their dad (my DH) as their mum doesn’t and they have no pocket money and I also sort presents for their mum for Mother’s Day, Xmas and bday.
Now am I missing something here?