That's not "how technology works". You're misinterpreting Moore's law, which is very specific on digital chip costs. That means Intel can make faster CPUs by selling more hardware. (Moore's law is dead anyway, but that's a different story)
The fundamental issue is that cell phones are power limited. Moore's law doesn't make a prediction on that. The main issue is that battery capacity has been stagnant for more than a decade. You can't cram in more hardware to improve speed until transistors become more efficient, or they come up with better batteries.
They're so desperate that your iPhone doesn't even use silicon in critical radio components. They switched to semiconductors unheard of in PCs (SiGe, GaAs, InGaP). The guy who figured out how to make the special transistors in your phone got his own Nobel Prize (Herb Kromer).
On top of that, laws of physics kick in. Basically the size of radio waves, how they absorb by buildings, available bandwidth, radio frequency safety limits. Look up "Shannon Limit". This is stuff that wireline communications, via cable and fiber, don't have to deal with (yet), but wireless does.
Therefore, your tower ends up having the same capacity, but demand increases, so you have to build smaller cells, and cost increases.