Engine oil is disappear

Toyota had a few issues with oil consumption during this era, which got fixed in 2007/8, the main known one with known issues being the 2AZ-FE (2.4L i4). It's known to get worse as the mileage builds up worse than it does on engines that lack it as a "known problem" as well, so it's expected on them as they get to be very high mileage cars. However, changing the PCV valve can sometimes fix this or reduce the "burn rate" if you want to try for $5-10. I'd try it if it were bad enough myself for that little. However, I tell people looking at these to EXPECT them to burn some oil if it's not from 2009 or up or has a problem engine like the 2AZ-FE. 2009+ is generally safe but can still burn a bit when they get to the point where the odometer puts off casual buyers. 2008-2009/10 can be fine but beware of the bad engines.

The 1.5L Echo engines likely are prone to it, too, like the 2AZ-FE is known for. It doesn't mean you have to junk the car, but you will need to do more frequent oil changes and change the spark plugs a little more often (ex: if you do 5k mile changes, go to 3k, 4k if you miss it max; change the spark plugs every 70,000 miles vs every 100,000). I would be fine with one of these "oil burner" Toyotas as an A-to-B beater car, even with this problem, because while they burn oil, they will still run for years without giving you a problem. Even when they have issues like the 2002-2006 Camry (VX30) and the 2AZ-FE VX40 Camry (less troubled but wouldn't trust them), they still regularly build up 200-300k+ trouble-free miles where the owners keep running them. Keep a quart of oil in the trunk and top it off as needed, as well as what you normally buy during an oil change. To make sure you know what gets used, you may want to do your oil changes yourself so you don't have to play the oil brand lottery where the shop uses something like Penzoil, but you may use Mobil 1.
Some people even have 400k+ on these "oil consumption" era engines if that gives you an idea of how little it matters. However, while I wouldn't be put off by it (or even high mileage), I would expect the price to reflect their problem and miles (I have seen them with 180k still running). Higher miles on a Toyota would not scare me off, especially if it's a 2007+, where it likely burns a little oil with how many have high mileage, but not to the degree the infamous engines burn.

The piston rings are the failure mode on these engines. They can be repaired with new rings, but you might as well rebuild the engine at that point since it requires full disassembly.

I totally agree with you as an Automobile technician when you say that One might as well rebuild the engine at that point since it requires full disassembly