The real reason we warn kids to stay away from the tracks. It turns out that confectionery is cheaper than gravel in some parts of the world (and resists water erosion better because of the wrappers). Sadly they didn't anticipate anthropomorphic erosion events such as this leading to extended rail line outages.
Once the secret was out it became a nation-wide phenomena for kids to raid the tracks.
Railway engineers have been attempting to address this problem by tweaking the infill composition. A recent experiment involved infilling with only licorice, however it turns out some kids still like it. Local newspapers claim the railway engineers were quite confused by this result.
On the right the girl's hairdo reveals she had a recent near-miss at one of these railway digs. The adults now keep an eye on things -- if you pay close attention you will notice that there is actually an adult (or at least teenager) in this scene. Analyse the image closely and you might spot it.
An aspiring railway engineer at the top of the sketch, wearing blue, is pointing out a flawed sleeper. Either that or he's making a fat joke about one of his friends sitting on it.
The dirt desire-paths around the tracks show that locals regularly walk this line. Maybe it's safer than you think? These kids might not have been the first to raid this spot (how did they lift the sleepers?), I suspect the adults cracked it open sometime last night. Usually rail workers cover these sites with a tarp and signposts within a day of reporting.
Prompt: "The lost powers of childhood. Group of children in a park next to a rail line, discovering flaws in the world. Chocolates are everywhere." Generator: Bing DALL-E
Yes it looks like it's adjusting the port length. (In plain english: some speaker boxes have an intentional hole in them, if you adjust the length of the pathway that sound takes to exit the box through this hole then you adjust how bassy it sounds).
To add a hollow cavity into the plastic part would immensely complicate the design of the moulds (assuming you try and implement the cavity in the same style & orientation of what gluing that bit of wood in achieves). The plastic shells of this speaker look like they've been designed for two-part moulds, which is the cheapest and simplest way of designing a mould. Any internal cavities of the part would require bits of steel mould to be in the cavity during injection, those pieces then have to be removed somehow and that would be a nightmare. Two part moulds can just be clamped & separated over and over again without snagging on anything.
For the walls of a speaker to reflect sound they need to have a density that is very different to the air inside the chamber. As it turns out basically anything fulfills this criteria, even cardboard makes fine speakers (just don't get it wet or poke holes in it). Plastic vs MDF wouldn't matter here acoustically, both are fine.
Bits of particle board can easily be cut and glued by unskilled workers. For business reasons the injection moulding might be getting done at a different place to the final assembly, and the product manager who wants the speakers properly ported might only be in charge of the latter. IDK.
I suspect this would be all human assembly. They'll probably have motorised torque-limited screwdrivers and jigs to hold the parts on during assembly, but still human arms doing the work.
In particular: stuffing the white polyester wadding in would be a PITA for an automated assembly machine. Humans are tolerant of variation and bits of wadding blowing away, pre-programmed movement robots are not.