Sunglasses reduce VLT across a broad band and often polarize the light that is passed providing glare reduction and better sharpness (dependent on the designed wavelength), so yeah you will see a reduction in brightness. That is the nature of sunglasses. But this in no way provides any kind of protection because you don't know when the lens will fail.
I realize most of the members on this site have no idea what standards are and why they are in place, but they are designed to save your butt, and in this case your eyes. Standards have been devised because people will always do the minimum they think is required to get by so manufacturers have to bear the responsibility, by law, to protect those who would otherwise allow ignorance to rule. It's just another example of the government protecting people from themselves. Unfortunately, those who would choose to injure, maim and kill themselves due to their own ignorance or incompetence, are not allowed to do so in modern societies. It would certainly deepen the gene pool which in today's day and age is much too shallow.
Lasers were never designed to be toys, yet here we are with kids capable purchasing laser pointers rated in the hundreds of milliwatts. It not from a lack of laws. It comes from a premeditated decision by foreign laser companies to cash in on people regardless of the dangers involved despite import restrictions by a country. Yeah, a "light device" on the customs form is an accurate description but funny, the harmonized tariff code is not what is in the box. That is an intentional violation of law designed for one thing, and one thing only: get a laser pointer into the hands of someone so we can profit without regard to safety, training, or the rule of law.
The facts are the facts; they are available. Because the manufacturers could care less if you blind yourself and countries that restrict the import cannot make these companies accountable nor identify all illegal imports, it comes down to the user to operate the systems in a responsible and safe manner. I've said it time and again, part of the responsibility of ownership and the cost of the hobby is to acquire the proper safety equipment so you or someone else doesn't become a statistic and set off a chain of events similar to what has happened in Australia. That is the responsibility you bear in owning a laser. If you cannot live up to that responsibility, you have no business wrecking it for everyone else.
I have no sympathy for anyone who takes a shot to the eye when it can be so easily prevented with the proper safety gear. I hear the famous statement on a regular basis, "but I cannot see the beam." You are not supposed to see the beam if a laser is used in a fashion for which they are designed. The whole idea of laser safety eyewear is to prevent the very light you want to see from reaching your eye. Some systems require visualizing a low intensity beam but they are for alignment purposes only; generally for much more powerful laser systems. Thus you can get safety glasses in low OD which often are perfect for lower power lasers. They are also very inexpensive, comparatively. I'm sorry if some of you cannot afford to purchase a laser and eyewear but that is the point I'm trying to make. If you cannot afford the safety equipment you should not be in the hobby.
I'm sorry if I have been harsh but I cannot stand by, with my background, and education in this industry and let you risk your vision because of hunches or flawed logic. Of course I cannot stop anyone from doing what they will but don't expect any sympathy from me. In fact, expect me to laugh and give you a really good, "I told you so speech."
Oh and here's a little food for thought. Everytime a laser related injury occurs and is treated, it is reported to the FDA (in the U.S. anyway). Those reports provide the impetus for lawmakers to restrict laser sales. Do any of you want to be the final straw that outlaws pointers like in Australia. It was ignorance by bafoons that got pointers banned in Australia. Don't blame the government. Yes, it was a kneejerk reaction but the government's duty is to protect all citizens and it certainly doesn't require a person to kill hundreds of people on an airliner to force a government to act. It will continue to happen around the world as a few idiots continue to spoil it for all. Do what you are supposed to do with a sense of responsibility and it will extend the time you are allowed to own personal laser systems.