Final answer:
A general-purpose AI is considered similar to a utility because, like essential services such as water and electricity, it would need to be accessible to the public on a broad scale.
Step-by-step explanation:
Researchers believe that a general-purpose AI must be available to as many people as possible, making it similar to a utility. Like a utility, a general-purpose AI would be a service that is provided on a wide scale to meet the public's needs. Considering that government-provided goods and services like national security and education are designed to be accessible to all without direct charges, utility is the closest comparison. Utilities like water, electricity, and gas are essential services that are regulated to ensure they are available to the entire population. Meanwhile, tax plans are related to the collection of revenue to fund various services and are not directly akin to providing AI as a service or utility.