You may need
WordPress hosting
It is built for WordPress: updates, caching and staging are handled for you, so you spend less time on upkeep.
How it decides
Traffic and the number of sites decide first, because they set the resources you need. WordPress and budget then choose between plans of that size. These are rules of thumb, not measurements of your site, and a heavy page can need more than its traffic suggests.
Not sure of your numbers? Use the bandwidth calculator, or read shared vs VPS vs cloud.