It's changed several times. For 2012/3/4 the manual release is roughly behind the glovebox. For 2015s it's in the nosecone. 2016s are as noted above. And those aren't hard dates, despite the First Responder's guides being labeled as such.
I would presume the cut loop needs to be protected from weather and risk of damage from externally. It may also have to do with the routing of it.
The Porsche ones are similar. One is under the headlight (more similar to Model X implementation). The other is in the front wheel well (either on driver or passenger side depending on model). They are in harder to reach places, but they don't serve an emergency function (it's primarily for in case the battery is dead, as their frunk uses an electronic latch). Plus their location is not documented, unlike with Tesla which has it for emergency responders.
From the original article:
Reviewing the 2021+ Refresh version of the First Responders Guide I don't see any cable release anymore for emergency Frunk release, only an electrical option that is disabled when the car still has low voltage. So the manual frunk release has been removed?
Page 4 shows they switched to the Model 3 system, which allows the first responder to jump the frunk release via the tow hook when there is no power. This design addresses both concerns: the need to open the frunk when there is no power, and security of the frunk during normal use.
For what it's worth, also wanted to add since this zombie thread was revived, since then there haven't been reports of widespread (or any really) accounts of people breaking into the Model S or X frunks. The methods Tesla used to hide the releases is enough to keep "honest" people out, and it's too much of a hassle for thieves to use. Instead what we saw were widespread accounts of people breaking the rear quarter glass of the Model 3 to drop the rear seats, but that's a story for another thread.
