How old do you have to get for them open stuff themselves?

There was this hilarious bit on the Carol Burnett show decades ago where she comes into her kitchen with several bags of groceries, hungry as heck, just starving, but she can't get any bags open. Eventually falls down, starved to death.

It is true they could/should make em easier.

She gives them to you to open because you're the man. It doesn't matter about age.

She's playing the game -- just play it with her.

I have had women assume, because I'm a male, I know so much about automobiles that I can look under the hood of their non-operating car and diagnose what is wrong with it. Not all guys can do that. I got a degree in accounting and know something about business and economics but my mechanical skills are limited.

She's using the Ben Franklin effect. Ask someone for a small favor, and they are more likely to trust you. The explanation has to do with cognitive dissonance: we adjust our attitudes to match our actions.