It’s really not that huge a jump. For a single phone line with tethering, ATT will run you $1200 annually. My budget provider with deprioritized service but on a similar plan is $540. A Prime membership covers a household, but anyway you measure it, $150 is close enough to “one order of magnitude less” to be useful as an approximation.
I seem to remember there not being any fees the first time I signed up, which was over two years ago but they were there 18 months ago. I’m assuming they didn’t charge them at the start to make the price more attractive.