I just grabbed LM7805 from National semi and it kept 5V output all the way up to 60V input voltage my PSU could supply. No input/output capacitors and load attached.
If someone designs a circuit based on tests like that or on datasheet limits, there will be a bad surprise later on. I can walk on one foot for a while, but the conclusion to buy one shoe only is certainly bad. The reason for not using a LM7805 with more than 20 V input is heat.
Only recently i fixed a Keithley 213 quad DAC (a rebranded IOTECH DAC488) that has four 5 V regulators running from 31 V input, all without heat sinks, at 55 mA each. That can't work. One of the regulators was burnt, although in theory they have built-in over-temperature protection. All capacitors were dry from heat, so the other three regulators were oscillating. What a mess.
Regards, Dieter