That's because the devs got lazy and did nothing but add the radio back into the drop tables without touching the code for the radio itself. It was working at one point a long time ago, but was suddenly removed from all drop tables. It was added and functional even way back in the Dean Hall days.
I datamined the code for this a couple of months ago, and said the following in another thread:
I'll extrapolate, because the code is still in the game and I've found it while datamining. There are four internet radio stations linked in the code, each referencing Absolute Radio, for use as contextual menu options for the ingame radio (not walkie-talkie, an actual radio):
There is no mention as to why the item was removed, but the radio item (Tool_Radio) is fully functional ingame, with accompanying model (unitra_wilga.p3d). The item does not currently appear in any loot table. Judging by the item's completeness, including its carrying animation, I imagine a Bohemia developer could summon one ingame at their leisure, should they wish.
Correction: The links for 60s and 70s are outdated in the game files, using direct IP links. 80s and 90s are properly hotlinked and working as intended.
Adding the radio back in was as simple as putting it back into a drop table. Letting us find this radio is simply the creation of the illusion of progress.