The AT Paras/AT PG/AT PF/AT ST/AT SP do not have snares at all. With the recent buff there is not reason for Penal to have snare (especially 1 shot ones) either.
That has a couple flaws in the reasoning due to what environment Penals exist in compared to those other units.
1. Penals lack numbers. It's common to only get 3 penals due to their cost and trying to get a 4th is so expensive it isn't really an option. You could get a conscript squad but if you want snares with them it's even more expensive than a 4th penal. So in the end you end up with in general 2 AI penals, a conscript squad, and the PTRS penal. This essentially means you have 2 frontline fighting squads and an AT squad.
This is in stark contrast to the examples given who all get at least 3 main line combat squads on top of the AT unit. For example with PzGrens you're already gonna have 3 grens/ostruppen/assgrens to keep battling infantry even if the PzGrens get the AT tools. This is true for the majority of the units listed outside of possibly the PzFus. The PzFus get away with it since it's very common for OKW to get 4 infantry squads starting off so they can get shrecks and still have 3 mainline infantry.
If you want a more fair comparison for Penals and what giving them PTRS are like, it's similar to having 3 Rifleman and giving one of them zooks or 3 IS and giving one of them Piats.
2. Penals don't have AT support. All of those examples have the option to also back up their infantry AT with an AT gun. This does not exist for penals without a massive investment to backtech for the zis or the use of commanders with the 45mm. Seemingly Penals shouldn't need to only exist with commanders that have the 45mm right? Well even with the buffs it's still largely going to be that as you can't just have a PTRS squad carry your entire AT capacity until late game. If you tried to use just a single squad of PzGrens with shrecks and use them to carry AT until a Pz4 it wouldn't go very well. Those other examples exist in a position where they have other means to stop armor and so the AT infantry is complementary. Penals don't have this luxury.
3. Other AT infantry have support to snare. Even if the AT infantry itself doesn't have a snare you often have 3ish squads that do have a snare to use together with the AT infantry to help kill vehicles. Penals get the single AT squad with a snare and to get a second snare have to get a conscripts and then get the grenade package which does currently nothing for the Penals themselves. In total that second snare comes out to 390 manpower and 15 fuel just so penals can have a snare. Compare this to like Riflemen which just have a snare after naturally teching up or things like Grens who literally just have a snare right from the start.
These 3 points in conjunction should show why Penals do need better AT capacity than their peers as they lack a lot of the tools those other examples have to support them. Imo making the AT satchel something any penal could get and lowering the damage to not one shot things would be a big improvement for them. It would give the Penals more of an actual chance to scare off enemy vehicles and keep them from diving/walking over the penals when the PTRS ones aren't around. The surrounding events of soviets going T1 just make it so Penals need stuff like a snare while also being able to get AT because they have so few tools otherwise.