Doctor's Answers (1)
Slightly over 2 years ago (Jan 2017), the results of the 'PROWL' studies were published in JAMA Ophthalmology. Many newspapers and magazines went to town with the complications that you ask about. You should look this abstract up if you are keen to get some idea about the quoted figures or read more about the PROWL studies here.
It is important to know also that the data only refers to a particular group of people in a particular setting (country, demographic, laser machine/technique etc). As such, there is inevitably a great deal of generalization.
This is the difference between doing an internet search/reading a newspaper article, versus going to a doctor, getting tests done, and then discussing the risks of certain complications in your particular situation.
For example, the risk of persistent halos is higher for people who have very high spectacle powers and almost non-existent for those with very low degrees. Nuances like this (which can be many) are best explained in the clinic, as there are many possible combinations and permutations of risk factors that are unique to the individual.
Certainly, if the particular person is at high risk of getting side effects/complications, then it is the duty of the doctor to advise against having such surgery. But at the same time, there are many more patients who will get good results from LASIK, and it would be doing them an injustice to withhold such effective treatment from them.