system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why do electonics that display the time (ie microwaves) not have a small battery to ensure the time to saved in the event a power outage?

My clock/radio has a battery and it costs approx 10‰ of the microwave.
gpt
A battery costs money. The circuit to integrate the battery costs money. Designing the circuit to integrate the battery costs money. Assembling the circuit to integrate the battery costs money. 

No customer at the store chooses which model of microwave to buy based on if it has a battery or not. It is not a selling point. 

So, adding a battery would cost extra money while not adding to the price the unit could be sold for. Appliances are about the bottom line.