The customer changed the requirements, then got upset when the price went up (a bit)
FFS - adding a USB charger (to a lunatic concept) is going to up the regulatory effort, which is the sort of thing you'd expect an engineer to notice.
"According to the court filing [PDF], Mills was hired to develop a battery-powered pump for an umbrella that incorporates a mist spraying system. After the client informed Mills that the device should support USB charging, Mills raised his initial estimate from $4,000 to $4,800. The client in response complained to the Arizona Board of Technical Registration that Mills was not a registered engineer and demanded a refund of payments made."