Encryption isn’t hard, the service to stream live data over an hour is what costs money.
Continuous data
It’s not continuous, and it’s not much data. It’s GPS coordinates once every five minutes and when it’s requested.
When you’re looking at the map, it’s continuous.
And it doesn’t sound like a lot of data until you compare it to text messages that are 2kb a couple times per day
The amount of data is a joke for location “streaming”. There is no need to update the location every second, most people on earth don’t travel with rockets. Updating the location at most every 30 seconds is probably more than enough for most usecases. Let’s make it 15s. Let’s be generous and just use two 32bit floats (could probably get away with 16bit half precision or fixed point). The size of the entire message (without meta data and encryption) is just 8 bytes. There are emojis that need more than that. And in practice people that can’t share their location often just end up sending images, so the amount of data is definitely not the issue with location sharing. A single image you send on Signal uses more data than streaming the location ever 15s for a few days.
See my comment here for the amount of data it would take to share updates for 24 hours, it’s almost nothing: