Safe mode disconnects some (mostly) 3rd party things from the system, because sometimes they screw things up. If you used Safe Mode all the time, you couldn't run unregulated 3rd Party software. There's no Safe Mode on an iPhone because the only software allowed on it is from the App Store. If you don't use any of that sort of software, you can run in Safe Mode all the time, if you like.
Since you asked, prepare for an essay:
Why did you have to dial a 1 before a long distance number? Well, you had to trip a relay to connect your phone to the long distance network. A better question is, why don’t you now?
Phone numbers have a 3 digit area code, a 3 digit exchange, and a 4 digit local number. An area code might be 212. An exchange might be 785 (and you’d call it RUsset-5, or RU5, because R is 7 on the phone dial (really a dial), and U is 8, and it’s easier to remember RUsset-5 than 785.) So your local number in Manhattan, NY, might be RU5-1234. Calling RU5 would click three relays, the first to 7 connecting it to another that clicked to 8, connecting to the third that clicked to 5, connecting to a local area sub-station. And those sub-station relays would click to your specific phone.
But, since 785 is the area code for Manhattan KS, if you dialed 785-1234, the relays might connect you to Kansas, instead. The relays would have no idea if you were calling local Manhattan, NY, or to long distance Manhattan, Kansas. So calling Kansas from New York you would dial 1-785-222-3333, or whatever, with the leading 1 connecting to long distance relays, first. As long as an exchange number could be like an Area Code number, you'd have to add something to indicate long distance.
This couldn’t change until, with the switch to electronic “touch-tone” dialing, a computer could process the entire number rather than having a relay clicking one number at a time. The 1 is no longer needed.
As an aside: Area codes never made sense to me. Manhattan is 212, Los Angeles is 213, Dallas is 214, Chicago is 312, but Manhattan KS is 785. Obviously the number is not connected to location. But, instead, it’s about how long the relay takes to click. For Manhattan KS (785), the relays have to click 20 times. For Manhattan, NY (212), there are only 5 clicks. There are way more phone calls to Manhattan NY than to Manhattan KS, so fast dialing for the big city, and large metro areas got area codes with small numbers. With computers, none of that matters anymore. So Dallas has both 214 and 972 area codes, and they take the same time to dial and connect.