I wonder if Indiana-Jones-style death traps would successfully show trespassers that the site's builders were serious, or if this would only attract more curiosity.
And honestly, Indiana Jones style traps would never survive 10 years of deferred maintenance, much less 10,000 years. Even simple traps like weak floors over spike filled pits would tend to rot and collapse over the years, especially if you need to build it lightly enough that a single person can trigger it unknowingly.
The only Egyptian tombs that survived to the modern era were the ones so well hidden that nobody had managed to stumble across them.
I was thinking the same. However, the problem is not to avoid people from getting in and causing harm to themselves, but them getting the dangerous stuff out and causing harm to others who actually heeded the warnings. You'd need extremely strong radiation