Well, the DMG says it's DC 20, which is hardly impossible. And an obvious trail only subtracts 5 from the DC, which means that a non-obvious trail is still only DC 20. A 1D&D ranger could get expertise in Survival at 1st level, meaning even just starting out, that ranger could get a +6 or +7 to their Survival roll, which means that--well, someone who's better at the math than I am can tell you exact percentages, but I'd say that a 1st level o5e ranger would succeed on a Survival roll for tracking the majority of time (and would also learn more information through tracking than a non-ranger would). And that's without any sort of magical aid--or without any special ranger abilities to make it easier, which could be added without making a sub-system. "X times per day, the ranger can get advantage on Survival checks made to track" or "X times per day, rangers can track creatures that fly or are protected by a pass without trace or similar magic without having any penalties to their Survival check."
Also, I have no idea what sort of spells you're expecting a ranger would use to help them track. Guidance, maybe, but that's been nerfed to 1/rest/target in 1D&D, and that's only going to average a +2 to that roll anyway. They don't even get locate creature until 14th level (and bards, clerics, druids, paladins, and wizards get it too--and except for the paladin, they all get it a lot earlier as well). And heck, they don't get faerie fire, see invisibility, or mind spike at all, and those spells actually help you find people!