Exactly. I haven’t even heard of a wifi data limited plan prior to this. Furthermore, calls via wifi need the other person to be online, don’t they? Calling is done through balance of the sim card, atleast that is so the case in my country. It’s either japan has a totally different wifi system or the author isn’t tech savvy.
Old shitty and outdated data plans are like that. Phone/internet company often times just wont let you know you can update your garbage limited data plan for a better modern one at the same pay rate.
Depending on your contract amd provider, such as satellite internet, you can have a limited rate and after passing it they throttle you hard. Even when using a lan cable to your modem gets throttled not just the wifi. Used to have that on my phone and my sister would destroy our family data pool in a week using... you guessed it, Instagram and facebook. I had to fiddle in the phone settings in order to enforce limits and divide the data pool among my family so we all had a fair share. Was fun negotiating for favors for me to allow her to use a gig from my share of data lmao.
Pretty sure wifi calls dont need the other person to be on wifi tho, whenever I call from home it automatically connects to the wifi and has a "wifi-calls available" symbol/notification show up and the audio quality is noticeably better. I can also recieve calls when the signal is really bad through wifi calling, which happens quite often.
So yeah, everything that happened in this chapter I've had to deal with personally. Doesnt make it feel any less out of left field tho, i never expected that twist.