I think, in the US at least, part of the problem would have been Verizon/Sprint. Now with everyone going to LTE and using SIM cards for that it seems more viable (fewer network restrictions).
Why is that a problem? Apple ships millions of 3G/LTE devices a quarter, they can certainly figure it out in the laptop form factor. Worst case and it doesn't support every network--still way better than not supporting any network.
The bigger issue is probably not having OS X architected to play nice when you're paying by the byte.
They shipped different models to handle different carriers and only recently are they shipping unified models for multiple carriers. As I said in another reply, that's bad UX for a device that's not quite at commodity level prices. You could always get a dongle or pair it up (still options), which prevents the computer from becoming obsoleted by changing network affiliations or protocols.
> which prevents the computer from becoming obsoleted by changing network affiliations or protocols.
Which would never be the case... Right now no Macs come with any mobile data and I somehow still manage to find them useful. If my MacBook had come with 3G it wouldn't be obsolete now that LTE is the rage, the worst thing that could happen is I would tether with another device like I do now.
I also have a Chromebook and I have to say it's nice not to even think about it--you're just online.
LTE penetration is still a huge issue. Then there's the question of band support (different carriers use different LTE bands - not all mobile data devices support all bands).
There're two reasons why LTE isn't a panacea to cell standards bifurcation and modern cell phones still require fall-back data radios that support EVDO, HSPA, etc.
They can now. Before we had (and on iPhone still have?) different models to handle different carriers. That's not a good UX for customers, especially as computers are still not at the commodity level that phones and tablets are (refresh purchases are 3+ years apart).
