Ice Cream: 15 years later still $1

Sometimes I would buy myself an ice cream like this for $1 after lunch at Boat Quay. That was easily 15 years ago. Tonight I bought this for $1. No cutback in the portion but meanwhile the prices at Swensens and elsewhere including Magnums keep going up.

So how can people like this ice cream seller not be suffering income loss over time? The guy who washes my car is afraid to raise his rate but the car wash at the petrol station isn't afraid. Big business is leading the way with price increase. The smallest businesses are taking home less every year. May be they often serve the poorer customers and so can't up prices.