From an american expat who lives in cdmx, Gordo definitely more correct than 'boss here. Uber is considered the safe / posh way to get around, and its certainly not some wild west. I imagine loads of people coming from usa will just take uber from cdmx to and from the festival.
Im still waiting to see if there is an official ceremonia shuttle between cdmx centro (typically, roma/condesa neighborhoods, which are the hip areas gordo mentions) and the festival grounds. Many other festivals do that. Transportation section of the official website still says "more information soon"
I was just in CDMX (on my way to SMA) earlier this year, and some friends (one of which is a Uber driver himself) told me and my wife this, and his friend who teaches English agreed.
Sure, the posh areas like Condesa I would assume are safe®, but right outside the international airport it is like day and night. You also need to realize that unless you know what you're doing, it can be easy to get lost/misled, especially if your command of the language is not strong. Living somewhere is a lot different than visiting.
I don't mean to strike fear into anyone, but keeping your wits about you is sensible.
I stayed overnight at CityExpress, and yes - it's clean and a bit sterile, but for a few nights' stay it's cheap and fine. Perhaps @Gordo or @Marked x One could suggest as good or better places to stay?
If you're just in transit City Express is ok. That's pretty much what they're made for; Express business trips (and unexpected sexy times). They're clean and discreet but you won't get anything else more from them.
If you're planning to spend some time in the city tho I think an Airbnb is the best bet. I don't really know much about hotels tbh, well located ones are probably expensive.
Re: Uber. Dunno man I've only been raped once and he was really nice, gave me a water bottle and everything after.
Kidding aside I can't recall a single instance of something bad happening at an Uber Ride, at least in cdmx. Beats riding a taxi for sure. But I guess your point is good, be attentive and call out whatever you feel is shady.