Not necessarily. The track width of the Tacoma is wider than the Hilux, so the axles are similar in the same way as they were in the T100 and now Tundras. The Hilux is 1,535/1,550mm FR/RR (60.4"/61") and the Tacoma 63.0"/63.2". All of Toyota's axles are similar in construction but there's nothing I can find that suggests the Tacoma axle is identical to the Hilux (which I would dearly like to be). So you nor I can say the axle tube walls are the same thickness, for example, to suppose without a doubt the payload capacity of the Hilux can be carried over to the Tacoma based on axle strength.
Also the parts are similar in other places. Like the control arms, spindles and ball joints are the same geometry but ball joints have different tapers. So I can't just put in 4Runner/FJC/Hilux ball joints (or actually control arms since Toyota no longer sells ball joints as replacement parts). The Tacoma upper and lower arms have a different part number globally than the other 150-derived trucks. The transmissions in the V6 haven't been the same for a long time. Similar Aisin family but different models and gearing. The 4 cylinder trucks have always been more closely related to the global trucks, though.
Track width is different...Does that mean the axles themselves are different or are different offset wheels axle hubs are being used? As far as I know, the Tacoma's 8.8" axle is pretty much the same as what the Hilux (and 4runner/LC Prado) use. If you have sources which suggest otherwise, please show them.
Some of the other chassis components (control arms) might have different numbers, but that could very well be due to internal/administrative purposes. Looking at the 4runner and Tacoma, a lot of the core chassis components seem very similar...perhaps not interchangeable but nonetheless similar. My point is, I don't think the Tacoma is lacking any of the special engineering and QDR-testing that goes into Toyota's global platforms. Even if the Tacoma's upper control arm is somewhat different from the Hilux's (which I'm not sure that it is), I have no doubt that Toyota incorporated its engineering and lessons-learned from the Hilux into the Tacoma's design.
And with Toyota's future plans to standardize some of its truck construction with global platforms, I think parts interchangeability and commonality will only increase going forward.
But to your point, the Tacoma surely is different, in some form or fashion, from the Hilux....so is the NA Ranger. Have you taken the time to do a detailed analysis of that truck as well? Because based on media reports, there are some obvious differences between the NA and global version (frame, rear axle, transmission). Is Ford incorporating all of the same chassis components from the global version?
The chicken tax impacts import of the truck. It wouldn't stop them from building the Hilux within NAFTA. They actually did that from 1992 to 1995, building the same truck in NUMMI in Fremont, CA, as they were building in Japan. The Tacoma was designed for the NA market intentionally and now sources parts from Dana and Delphi as often as Aisin and Denso. But OTOH Denso and Aisin supply plenty of parts to domestic companies, so the differences are shrinking in the whole industry.
I guess from Toytoa's perspecitve, it didn't make sense to try and build the exact same truck in North America and overseas. I agree the early Tacoma was very much "designed" for the North American market. Nowadays, the North American market demands more robust and more capable midsized trucks. I would not be surprised if the Tacoma and Tundra production becomes more standardized and aligned with Toyota's global offerings as time progresses...cuts costs and people want increasingly want trucks that are similarly designed compared to the global offerings.