There are various other possibilities as well, for example it's quite common for the production department to make changes to reduce costs.
The poor designer might have designed it well, and the prototypes performed as expected - then production mess it up!.
I had a LONG!! running argument with Sony over repeated failures of the mains transformer in a 100+100W RMS Sony amplifier (it's internal thermal fuse failed after about 9 months). My argument was that the mains transformer was far too small for the job (the amplifier was rated at 100W per channel continuous sinewave, both channels driven), which was why it kept failing. Comparing the size of the transformer to other toroids I estimated it to only be rated about 80W - in my opinion, FAR too small.
The amplifier itself had plenty of room for a larger transformer, and I've always assumed it was designed with a larger one?, and production fitted a smaller one to save costs!.
BTW, the cost of the proper Sony (too small) transformer was something like 150 GBP - a much larger, properly specified, transformer would only be about 25 GBP.
Sony's only comment was to offer 10% off the price of the transformer, and that they have had very few failures of the transformer.