Wifi is not on the chart. The chart is based on the "FCC ONLINE TABLE OF FREQUENCY ALLOCATIONS". [1] That table has 3 columns of data, the first two columns are what you see in the chart above. The third column is where the wifi frequencies are defined (among some others), listed as "RF Devices (15)" since wifi falls under Part 15 of the FCC Code of Regulations. [2]

[1] https://www.fcc.gov/engineering-technology/policy-and-rules-...

[2] https://www.ecfr.gov/current/title-47/chapter-I/subchapter-A...