People complain because their Fitbits, Garmins or Apple Watches aren’t perfectly accurate. Here is some perspective.
This is a pedometer:
It is what people used to wear to calculate distance. It was inaccurate, noisy and unreliable. It only measured distance and it was accurate within about 20%
This is a Fitbit:
It is what people now wear to measure activity. It is much more accurate and reliable than a pedometer. It isn’t perfect yet but it is getting better. For measuring distance it is accurate within 5%. It also measures time, heart rate, steps, calories and stairs.
Life is good and getting better.