The only reason for government based licenses is that governments like to have control and other people in various professions want to artificially limit competition.I don't necessarily disagree with him that licenses are used to reduce competition. That is definitely a downside, and in some cases is intentional. That is not the reason for licensing. Licensing is used for professionals who require a certain amount of knowledge or skill to perform their profession.
I'll use land surveying as an example. On occasion I have heard of people who have set their own property corners. They will helpfully show you where they are, and how they went about putting them there, with their Stanley tape measure, no doubt. Obviously they don't know it is illegal to do this. We would listen politely and then ignore them. Even if they are in the correct place, they don't hold any legal validity. They must be set by a licensed Surveyor for that.
There are methods, and standards of care, and some legal knowledge that is required to properly perform a survey. Some expensive equipment, that the average guy doesn't have.
If a license wasn't required, joe shmoe could go out and set his car axles for corners, and they would be just as valid as anyone else's, despite their being 5 feet off from the correct location. The next door neighbor, not liking the lack of precision, could go out and set his own, leading to a dispute. That would be one benefit to licensing. Land Surveyors sometimes get it wrong, but not nearly as often, and respect for the license will prevent some disputes. There are correct procedures that are used for establishing lost corners that a licensed individual must know. There are standards for setting monuments, that display the surveyor's name and license number so the monument is identifiable as to what it is, and who put it there.
Now could a private firm certify land surveyors? I suppose. So you hire one endorsed by a private firm because you want it done correctly, and your neighbor hires a bum off the street and slips him and extra five to take an extra five feet. Who decides which one is right? More needless court action.
With regards to Engineering. Do you want to live in a building designed by a licensed engineer who met the requirements for obtaining a license, or do you want to live in the one designed by an idiot who bought the drafting software? Nobody would ever lie, overstate their qualifications or experience would they? Sure your family can sue him after you are dead. But they won't collect, he won't have any money, and you will still be dead.
How about the engineer who has been in practice for 40 years, has a stellar reputation, but isn't up on the latest information? We are required to have continuing education to keep our license. I will admit, the continuing education as it is right now can be a joke. The threat of having your license pulled is also an incentive to be careful, in cases where lives may not be at stake.
As far as private certification, yes it could work in theory. But then you have the opportunity for someone to fake the certification, or competing endorsements. One costs a lot of money and you have to prove you know your stuff, the other you can get out of a cracker jack box. Anybody can make up a website telling how they've been certifying the best doctors for decades. Worse, there is no way to stop malpractice, and in some cases, malpractice is in the client's best interest.
As for the government using licenses as control? The problem is not licensing, it is over-reaching government. Some occupations really don't need licensing.
Now the system of licensing is far from perfect. (I should know, I've got two of them.). Sometimes the barrier of entry is too high, and sometimes there is an old boy network in control of the process, as I am lead to believe about a state to my east. Lawyers have licenses, and look at what boon to the public that is. Most professions predate licensing.
However, sometimes barriers to entry are not just for limiting competition. They are sometimes used to keep the morons out. Public safety is a good reason for licensing, even if it is just a hairdresser spreading lice.