I’ve definitely seen very high visibility in real life, and it can vary a lot depending on the area you are in. Flying off the coast of southern California in the warning area W-291 on San Clemente Island, on good days I’d regularly have visibility like what you see in the sim. Flying in the Persian Gulf, visibility was often poor due to blowing dust and the warm water leading to high humidity and haze.
Also, I think one issue is that the base weather data IRL doesn’t typically give a large-scale picture on visibility outside of the terminal area, e.g. METARs and what not often don’t report horizontal visibility greater than 10 miles. To my understanding, automated systems reporting visibility at airfields use laser systems that measure at most a distance comparable to the size of the airfield and not looking out towards the larger environment. Meteorology staff on site giving a report, even if in the tower, can only see a relatively short distance out compared to an airborne aircraft. Aircrew giving a PIREP might say the horizontal visibility but often don’t; if they do, unless they have a specific visibility distance, saying something like “unrestricted” or “unlimited” visibility may be subjective or interpreted subjectively by the person entering the report into the system.