I simply cannot imagine buying a phone without a headphone jack. I want as few things as possible that I need to keep the battery life of into account in my day to day life. Phones and laptops at least have display symbols for the battery life by default, I have never seen anyone in my country using cordless headphones that had some sort of indicator for how much battery charge remains in them. If some are sold in the first world then they would be out of my expense, and if there are apps available that would solve my gripe I have not encountered them. I do own a pair of my own, but I only use it in very niche circumstances for which I will have known to have charged it right beforehand, and I am lending them to family/friends more often than I am using them.

Even supposing that the battery thing wasn't an issue, the other hassles involved with going cordless (I've had to help people find them one they fall out of their ears way too many times for one lifetime) forbid me from ever even thinking about buying a phone without a headphone jack.