Heavier, yes, but having the form factor of a very tall front end is not a requirement for EV design.
Here's an article from 2011 predicting our current automotive market: https://me.engin.umich.edu/news-events/news/cafe-standards-c...
And here's the relevant section that called it from the get-go - emphasis mine:
At issue was this: Some companies offer full model lines, from cars to large SUVs and pickups, but some don’t. How could there be a overreaching fuel-economy standard that penalized companies like Ford and GM, while carmakers that sold only smaller cars effortlessly abided by the rules? So the concept of vehicle footprint was added. Models that ran large, crossing specific length-by-width thresholds‚ would have less ambitious fuel-economy targets. While the Obama administration has pushed for more aggressive CAFE numbers, the amended regulations retain the footprint-based leniency towards bigger cars and light trucks.
The result is a loophole, allowing the entire auto industry to sidestep some of the more painful efficiency requirements by inflating vehicle footprints. And historically, drivers almost always lean toward larger vehicles. “In general, if everything else about the vehicle is the same, consumers prefer the bigger one, with the roomier interior,” says Kate Whitefoot, a senior program officer at the National Academy of Engineering and the lead author of the paper (she was a doctoral student at the time of the study). Combine a regulatory loophole with a built-in, well-known customer choice, and the industry lurches towards the inevitable: larger models and more light trucks.
It basically allows you to depreciate it over 2-5 years. That's it. Pay back the value difference in taxes when sold.
There was a brief Bush era credit on top of this, long expired, but that still haunts the interwebs with rumors of still being prescient. It's not.
Iirc, the weight cutoff is currently something like 7000 lbs, and many suvs have nominal weights of 7001 lbs, with submodels that are 6999 lbs, for locals where getting taxed as a business vehicle is a bad thing.
(Unless by taxed you meant CAFE accounting, which is different.)
(I'll address a small area of CAFE besides what a commenter said about CAFE below, which appears to be entirely correct and on-the-nose to me re footprint.)
People for the most part didn't want larger trucks. They want the old smaller full size trucks. They are no longer an option.
CAFE targets (among other reasons) have forced the market to switch to Aluminum from Steel, because you can achieve near equal performance, with lower mass and higher mpg.
The cost is that aluminum is not as strong as steel, so you need more volume for equivalent strength. Plus the literal cost $.
But the cheat code is that moment-arm is proportional to force, but also length-squared. M=P*L^2 and similar.
So you can make some design elements lighter by switching steel to aluminum and making it bigger. Boxier.
Bonus is the then new-ish popular idea of crush zone is practically baked in with the larger, lighter, less dense designs.
Add in some addl (Steel to Al) complexity due to serviceability, flexure, and fatigue, (which require addl bumps in mass and/or length/ volume to meet design requirements), and extrapolate over the whole vehicle, and you get the size changes from roughly 2008 (cough, cough) to now.