What do you use in-car wifi for, that you couldn't already use your existing unlimited cell data plan for? I have unlimited data, plus "unlimited" hotspot on m

What do you use in-car wifi for, that you couldn't already use your existing unlimited cell data plan for? I have unlimited data, plus "unlimited" hotspot on my t-mobile phone for a really reasonable price (the unlimited hotspot throttles down after a certain point, but even that speed is still plenty for what I used it for -- I only which I could explicitly tell it I want to use the throttled speed gigabytes now, and save the high-speed gigabytes for when it would be useful).