I can *imagine* some of the answers revolve around... minimal environmental impact. I'm not saying that's the answer, but I tend to find a quick and simple solution when I see a plot hole so I don't dwell.
They're trying to start fresh and not make the same mistakes. So, they're probably trying to start out by minimizing their affect on the surrounding wildlife as minimally as possible. Hence no cell towers, and lots of walkie talkies.
For helicopters / planes I imagine environment + resources. They probably don't get loads of stuff from the future... and human-ridable aircraft need a LOT of maintenance and fine-tuning to remain safe. No to mention I doubt there are a lot of places to land if something goes wrong. And lastly, besides worrying about pigeons... you have to worry about pigeons with teeth that might want to try out the new + noisy prey flying around.
And lastly, depending on how much they start from scratch... I'd say they accomplished a lot. A small group of people starting from scratch takes a long time to get going. I recall fans complaining towards the end of Star Gate Universe... on that show you find out that a few dozen people got sent to the past with nothing but the clothes on their backs and some guns and wound up in the wilderness. Fans were complaining that "they should've been able to make an FTL ship in 1 or 2 generations." Umm, sure... they just need to survive the wilderness, grow crops, mine for iron + titanium + copper + whatever else, SCOUT for those materials, build stuff, all with a few dozen people.
It really depends on how much "stuff" the future is able to send them.