tsteele93 :
The eyes can heal in some circumstances. But that is probably the case only when cells are not destroyed by the laser (inflammation, bleeding, etc.) In other words, the disruption around the blind spot might go away, but the fried cells will still be dead. (To be clear, I agree with you that most low power laser injuries will not necessarily result in catastrophic eye injury and that some of the initial "damage" will go away in the following weeks/months.)
As you say, green lasers without appropriate filters can have a much higher power than what is advertised or visible. In theory, selling a laser as a 5 mW but with a higher power is illegal. All commercial lasers are required by the FDA to have the MAXIMUM power displayed, regardless of the wavelength (although the wavelengths should also be displayed).
That fact that there are few reported injuries does not mean that they do not happen. The scientific papers rarely report laser eye injuries anymore (because there's nothing new to say about it). (For example, there where more than 10 laser eye injuries in my university in the last 10-15 years. None of them were the subject of papers, not even articles in the local press.)
I would think that the absence of injury reports comes more from the fact that people probably don't want to talk about those (maybe minor) injuries and the fact that, as other people mentioned already, it is probably well known that you need to manipulate high powered lasers with respect (greater than 5 mW).
The safety factor is 10 for most maximum permissible exposure (MPE) calculations in the standards. For example, a 532 nm, continuous laser has a MPE that corresponds to a 1 mW of power entering the eye for 1/4 of a second. Meaning that around 10 mW of power into the eye for 1/4 s will result in an injury visible upon medical examination in around 50% of the exposures. A lower power will reduce the probability of injury and higher power will guaranty it. The limit of 5 mW (for class 3A-3R) lasers is there for that reason : a direct -accidental- hit with the full power of a laser in the 1-5 mW range might not cause an injury. So for professional use ("educated about the possible consequences of exposure"), eye protection might not be necessary (depending, of course, on what you actually do with the laser).
That being said. It's not because are exposed to the direct beam of a 50 mW laser that more than 5-10 mW will enter you eye and cause an injury. The beam diameter might be to big to let all of its power into you eye, the beam might not stay in one point on your retina long enough to cause injury, etc.
Safety glasses have to be selected for each laser depending on its power and wavelength. The purpose is to reduce the power below the MPE (about 1 mW if we use the CW 532 nm example again). If you use OD 3 glasses for a 50 mW laser, you will, as you say, be disappointed by the brightness. (You could also be disappointed even with the correct glasses, since you can't have both 100% safety and high power at the same time.)
I agreed with what I think is the basic message of your post : you have to be careful about how you use your laser, and that each person has to decide what level of risk they want to take. My point was that, from a strictly physical/biological point of view, the limit of what is or isn't dangerous is clearly known. You have to be aware of those limits when you make the decision to not wear safety glasses.
Finally, as I said before, I use laser in my work and would never work without glasses for class 3B or class 4 lasers. I will also wear glasses for class 3A/3R, depend of the application. Now, using lasers for fun is another thing entirely (part of the pleasure, I imagine, comes from the high power).
P.S. The potential for chronic injury (following multiple, long exposure to the diffuse reflection (spot) of a high power class 3B or class 4 laser, for example), as the OP pointed out, should not be neglected. (And the examples of calculations I gave are not valid in those cases.) It is particularly dangerous because it's more likely to affect the macula of both eyes and the damage is cumulative.
