Same here! If I'm only in a country for a couple of weeks, I'll just stick with Fi. If I'm there longer I'll pick up a local sim as it's usually way cheaper.
Do you find you need to use Speedify and tether often?
I wonder if speedify is detected by the carriers - most SIMs outside my country appear to have heavy tethering restrictions.
What you are complaining about is the US Cell market, which is awful and has horrible prices compared to the rest of the world.
I usually buy a local sim card for data because it's usually cheaper than Fi per GB. However, I pick a different carrier than what I can access through Fi so I have more reliable access for work (and can use both using Speedify).
Having immediate data on arrival, a backup cell network, up to 10 data sim cards for free and access to my US phone number and it's incoming/outgoing calls via data on Hangouts is a godsend when traveling and working remotely.
And while you can end up paying $80/mo if you use >6GB, you won't pay any more than that even if you use more (though they will start throttling you at 15GB).