Why does it cost me more?

I am a US American living in a major metropolitan area of Mexico. I first started using Uber in 2017 in the USA. I travel with a Mexican a lot in Mexico. Lately we have been comparing prices for the same rides. Mine is ALWAYS more expensive. Sometimes just a couple of pesos, sometimes many. The other day a ride to the airport was 390 pesos on her phone and 620 pesos on my phone*. Other times it has been 35 pesos vs 55 pesos for short rides etc. Form of payment does not make a difference. What gives? I am used to paying a small gringo tax for some things, but UBER?! What gives?

*we used her phone to Uber to the airport and I gave him a 100 pesos tip to buy dinner, and told him it was because it was a long ride for only $390. So I split the difference.