SF Bay Area <-> Las Vegas certainly gets a lot less traffic than either SF <-> LA or LA <-> Vegas, since it is a 10-hour drive, but there is traffic nonetheless, and not a lot of supercharger capacity cutting between I-5 and Barstow, Mojave is basically it. Only 18 months ago, I found Mojave to be a total sh**show mid-week in one of the lowest travel periods of the year - no V3 chargers, less than a dozen urban/V2 chargers and having problem (52 kw max at the time). Plus with most of the superchargers near Buttonwillow (I-5) and Barstow/Yermo still V2 (meaning avg 72 kw or less), pretty much EVERYONE had to stop at all three areas, not just me with my lowly 230 rated miles, to charge at 72 kw or less at all three places.
I know things are getting better now, and more coming, with more sites, more stall, and more V3, inc Mojave. But Tehachapi is basically not far from Mojave, and to me fairly equivalent to putting more at Mojave - they're close enough it won't change anyone's calculation about where they stop or skip at either I-5 or Barstow/Yermo. And I don't recall there's really any other major places along that corridor.
As to Tehachapi being at the top of an elevation and limiting regen, most are not charging to anywhere near 90%, plus I don't recall needing to do a lot of braking along that route, more like driving 70-90 mph, which will bleed off a pretty full battery in short order?