Yes, pay as you go can be costly. A few years ago i signed up for a month International plan with verizon for a 10 day trip to Thailand. Well, something went wrong and didn’t work right. I got home and got a bill for $2200. I called Verizon and straightened it out but good example of cost of pay as you go. And most of time there was no service so can’t imagine what bill would have been if there was.

Even if you are renting a phone or buying a SIM card, no harm in signing up for the International plan because costs nothing if don’t use it. And if you accidentally turn on Data while using WiFi at hotel or something cost will be minimal compared to paying for local Data ......