Sometimes exceedingly tall or short people will prefer that their cabinet and countertop heights reflect their stature. Those considered to be of average height typically adhere to the non-issue of industry standards. Cabinetry above cooktops is designed based on safety.
Safety
According to Home Construction and Safety Title 24 CFR, part 3280, there must be a distance of 30 inches between a cooktop and the cabinet that sits just above it. Adjacent cabinetry may narrow the gap to just an 18-inch expanse (if cabinets exist on either side of the cooktop), but this is the only exception to the rule. This is the same whether the cooktop is gas or electric.
Variations
Not all cooktops will have cabinetry above it. Some contractors and homeowners opt instead to install exhaust fans above the cooktops instead of cabinets. This is helpful for removing cooking odors, smoke and fumes from the kitchen, and it poses less of a fire hazard than a cabinet. Some appliances like microwave ovens are installed above the cooktop. They are protected with insulated undersides to prevent fire but still should be close to 30 inches above the stove.