I graduated as an Electrical Engineer in Brazil.
And most universities in Brazil give you 2 years of extensive background in all major areas of physics before they start to teach you the specialize aspects of your choice. In my case electronics.
Anyway, during the 2 years of general teaching, we did several types of experiments in multiple occasions. One of the most basic experiments we did was the measurement of gravity.
Anyway, all engineer students all over Brazil do this experiment as well, and in every city the gravity found is a bit different from the other cities. Gravity is never the same anywhere in the world. The difference most of the time is small, but it is in there, but sometimes the difference is so big that you cannot discard as a statistic error.
So I know by first hand this phenomena is real.