My guess is that your “fairly new Toyota” specs synthetic.
It isn’t a marketing ploy. It’s because, as others here have already said, engines run far cleaner than they used to AND oils have improved.
The biggest factors IMHO are that engines are built at the manufacturer to ensure that dimensions remain well within the statistical “normal variation” and not allowed to drift away from the optimal dimensions to the standards they used to be allowed to. This is done by applying sophisticated applied statistics to the manufacturing processes and monitoring and reacting to variation rather than simply dimensions. This has implications beyond just consistence of parts. It also allows analysis of fault cause as well as monitoring of the need for preventative maintenance on the machinery, and adjusting of the machinery maintenance schedules.
Additionally, amazing design software that can predict thermal profiles, stress propagation, finite element analysis, and other technical issues is now ubiquitous… and much of it didn’t exist twenty years ago. This allows design improvements, materials changes, etc. before the first metal chip is cut.
Another biggie is extreme advancements in fuel management. This prevents unburned and incompletely burned gasoline from washing away oil and leaving deposits on valves, pistons, etc. etc. etc. Modern fuel metering systems are light years advanced from where they were twenty years ago.
Even Exhaust Gas Recirculation, which replaces a bit of oxygen in the induction system with spent exhaust gasses, are being eliminated in favor of the new Variable Valve Timing, which also reduces contaminants.
And oil keeps improving.
However, if you feel uncomfortable with going 10,000 miles between changes, as do I, simply change the oil at an interval that you prefer. One objection that I have to 10,000 mile intervals is that far too many people don’t check their oil on the dipstick. And chronically letting it run low will cause premature wear.
My 2005 Toyota (Scion) doesn’t have an OLM. Neither did my 2005 Corolla. It would not surprise me to find out that a lot of cars don’t have OLMs. I wouldn’t trust them anyway. I prefer a dipstick combined with reasonable change intervals.