Meaning of One thousand dollar “luxury” bag.
You: Evidence of vanity at the cost of hard labor of poor daughter. Shameful object.
GF Mom: Evidence of daughter’s gratitude for all the hardship of being a poor single Mom. Proud object as it reminds of daughter’s affection and love.
GF: Small token of gratitude for all the hardship and suffering of her single Mom she witnessed as she grows up. It reminds her that she is now grown enough to give back to her Mom. Object of pride.
Your GF may have been happy for the time that she worked at the restaurant because it enabled her to get something for her Mom.
Money has different value and meaning to different people. I’m sure your GF would be completely surprised and then horrified that you’re thinking her gift of mildly luxurious bag as a sign of exploitation. You are turning something beautiful to something horrible. It’s because you can only look at money from materialistic point of view.
I don’t think you are a bad guy. You just have very narrow views.