Because the wrap doesn't matter. It's the membranes on the cylinders not the plastic around the circumference.
The affect of adding a wrap, or any mass to a shell, is hugely contextual in terms of how that feeds into the characteristics of the finished instrument. In most cases, any difference is inaudible, but in certain specific constructions, it can contribute to a change. In almost all cases, the hardware, by virtue of it's greater mass, offers a much greater influence, but even then, the change in audible delivery is likely more nuance than night & day.
Most players are familiar with the audible difference between a thin shell & a thick shell. The key influencing elements are mass & rigidity. Change either, or both of those elements, and the instrument delivery changes too. Again, the audible change can be small - non existent in many constructions, but in others, it's definitely noticeable.
This old clip, in itself, proves nothing in terms of finished instrument delivery (it was produced just to disprove a statement on pitch change due to mass), but it does give you an idea of the affect of adding a relatively modest amount of mass to a shell.
