Please rate my argument essay, thank you!

Here is the argument that I wrote recently. Could you please have a look at it and give some some feedback to improve. Thank you very much.
The following appeared as part of a letter to the editor of a local newspaper:
"It makes no sense that in most places 15-year-olds are not eligible for their driver's license while people who are far older can retain all of their driving privileges by simply renewing their license. If older drivers can get these renewals, often without having to pass another driving test, then 15-year-olds should be eligible to get a license. Fifteen-year-olds typically have much better eyesight, especially at night; much better hand-eye coordination; and much quicker reflexes. They are also less likely to feel confused by unexpected developments or disoriented in unfamiliar surroundings, and they recover from injuries more quickly."

In the proceeding argument, the author maintained that 15 years olds should be eligible to get driver licenses because people who are much older can retain all of their driving privileges by simply renewing their license. In order to support his opinion, the author listed out advantages 15 years olds owned: better eyesight, much quicker reflexes, and so on. For the first glance, this argument has some merits; however further considerations tell us that the author presented a poorly reasoned argument. Based on several questionable premise and assumptions, this argument can't be accepted as a valid one.
The primary issue with the author's reason lies in some unsubstantial premises. The biggest mistake the author makes in my opinion is he puts the fact that old people have the eligibility to renew their driving licenses together with the case that young ones get new licenses for the first time, and more over, he argues that since the former one can happen, the latter also has the reason to happen. As far as I am concerned, these two things are totally unrelated: one' eligibility does not necessarily guarantee the other's justifiability. First, renewing the licenses is different from getting a new one. People can renew their old licenses without passing another driving test because they have already gotten the qualification. What is more important, these people have already had rich driving experience, which I believe is a huge difference the case that getting a newly driving licenses. Second, under the analogy the author makes between 15 years olds and old people, he assumes that the 15 years olds own the same advantages as old people do, and own additional advantages that old people don't have, for example, the better eyesight, much quicker reaction, and so on. Our common sense tell us that the critical factors related to driving process are far more than that, and I suspect that the author misses some purposely in order to favor his argument. For example, the rich experience on driving and dealing with some accidence, and the stable psychological quality when coming across sudden and dangerous situations, which are valuable characteristics old people own. The author's premises, the basis of his reasoning are problematic, make its conclusion invalid.
In addition, the author makes some assumptions which are vulnerable I believe when he tries to reason his argument. For example, he says that 15 years olds have much better eyesight, especially at night, and also, they recover from injuries more quickly. By citing these, the author believes that these are the advantages making young people getting licenses eligible. It is not always this case in my eye. Just because young people have these characteristics, they usually tend to drive carelessly, for example they choose to drive at night with a high speed, which make their driving more dangerous.
In conclusion, the author's illogical reasoning based on unsupported premises and incomplete assumptions that render his argument problematic. In order to persuade the readers, the author should provide evidence to convince that 15 years olds have the enough merits like old people to be qualified to get a newly license, in which way the author's reasoning will be more thorough.

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