Hi
It says
here, "Off-shore, military, textile industry, marine, computer mainframe, aircraft, and spacecraft applications sometimes use 400 Hz, for benefits of reduced weight of apparatus or higher motor speeds".
I don't think there is a sharp line between AC and DC motor use. You have to look at the history and available technology of the times. Then, there is reluctance to change what works to something that is new.
For example, 400 Hz was used in aircraft because of the savings in weight for components, namely transformers. However, that 400 Hz was generated on board from batteries by a DC inverter. Many gyros for attitude control still used DC brushed motors in civilian airplanes -- at least until recently (my experience with aircraft instruments is relegated to the 20th century). Solid state sensors may be replacing those motors.
With the advent of solid state devices and microcontrollers, brushless DC motors became much more accessible. Their speed is quite easily controlled, and radio/HF interference is far less than with brushed motors. Thus, they find increasing use.
In early automobiles, where weight was not such a concern, DC motors prevailed as they were easy to use from batteries. Windshield wipers, as an example that today runs from an electric motor, historically ran from manifold vacuum, which could also control speed easily.
While DC motors have high starting torque, so do multiphase AC and brushless DC motors. Model aircraft almost exclusively use brushless DC today. However, on my lathe, I use a brushed DC motor with PWM control. It has very high, low-speed torque and no hesitation at the start. Hesitation at start-up is one thing you may see with brushless DC motors.
John