In that case, I'm not sure whether the borosilicate is obviously the better choice. My biggest concerns is not having the container break in my lunchbox rather than the thermal shock. Which is generally more durable to physical shocks, borosilicate or tempered soda-lime? And then, for the given durability, which is more cost effective?
The chances of being not damaged by a shock depend both on the material and on the wall thickness.
Because they are intrinsically less resistant, the tempered glass objects are typically made with thicker walls.
The end result is that the borosilicate glass objects with thin walls have about the same mechanical shock resistance like the tempered glass objects with thick walls.
Nevertheless, because the soda-lime glass has greater density than borosilicate glass, combined with the fact that the tempered glass objects have thicker walls, makes the tempered glass objects much heavier.
Their great weight makes the tempered glass objects more prone to being dropped during handling.
The borosilicate glassware is more expensive, but the difference is not significant, especially for objects that may remain usable for an entire human lifetime, if used carefully. I have never hesitated to buy some borosilicate glassware because it was too expensive. The main problem has always been that there are few suppliers so it may be difficult to find the exact size and shape that you search.
How is soda-lime glass “hard to get”? The main reason why it's still borosilicate here is because the brand has been licensed to a different company, and their management hasn't chose to stop selling borosilicate.
I'm just going by what Wikipedia says:
"Since the closure of the soda–lime plant in England in 2007, European Pyrex has been made solely from borosilicate."
Something like 30 million plus of glass was made in the EU27 in 2007 in over 200 facilities, nearly all of it would be soda lime glass (i.e. "normal glass"). https://climate.ec.europa.eu/system/files/2016-11/bm_study-g...
In Europe, Pyrex still uses borosilicate glass because it's better and because Europeans are more discerning consumers than Americans. That's my theory anyway. American pyrex cheaped out by switching to soda lime glass.
Wikipedia disagrees with you:
"Since the closure of the soda–lime plant in England in 2007, European Pyrex has been made solely from borosilicate."
Europe makes huge quantities of soda lime glass for a myriad of other applications, soda lime glass simply isn't hard to get in Europe. Wine bottles to windows, all that stuff is soda lime glass; borosilicate glass is a specialized glass that isn't used for most things besides cookware, labware, and sometimes lenses.
We do have glass in some of the windows, you know.
They're still glass (tempered soda–lime glass), which is what the OP was talking about, so you're just being needlessly pedantic without adding anything to the discussion.
Also, Pyrex is still borosilicate in Europe, since soda-lime is hard to get there.