Why Do Cheaper Bikes Use 21 Speed Gears But More Expensive Ones Dont Have The Front Three Gears?

Why Do Cheaper Bikes Use 21 Speed Gears But More Expensive Ones Dont Have The Front Three Gears? Why do cheap bikes have more gears than luxurious models? Cheaper bikes have more gears because they rely on a basic and mass-produced triple crankset technology naturally resulting in a large number of chainring to cog combinations.