Which is why nearly every pro player looks to their box after every point and many get warnings in each match? I don't think your argument holds based on visual evidence. They are getting coached during matches too.
How about 99% of the players at the collegiate tennis level are not pro level quality. Just like football, basketball and other sports. 99%+ do not go to the next level. Statistically true.
I don't know what matches you are watching, but I know for a fact, good players, do not look to their box for coaching after EVERY point. ( looking for affirmation and maybe a fist pump is completely different) Facts are, most players do not look to the box for coaching. Roger Fed. played many years and won majors without a coach on the payroll. Yes Rafa has been warned may times for coaching but I think he is the exception, not the rule. And the I doubt very seriously the stats show that most players do. So people truly will choose not to cheat. As a former tennis dad, Iwould never give signals or coach my kid from the sidelines. Yet I loved it when others would try because I knew, if the kid was focusing on the parent as well as my kid that he is playing, and had to keep focused on their strategies, keeping their game intact, it was going to be a long day for them. We prepared for matches in practice which took away the need to look to the sidelinens for coaching, but she would look for encouragement which is fine. Anyway there is a difference between a player looking to the box for affirmations and a player looking for coaching. Besides, some coaching is allowed at the pro level, just not every point and it is player requested, not coach initiated.
I do agree that a very small number of pro quality players are in college. And rightfully so, because most colleges will destroy a players development as it stands now. And for the players that are, and are pro quality, unless they continue to train with their personal coach, their game is doomed. Oh, and if you don't know, times has change and the time frame of a players development has changed. No longer will teenagers dominate pro tennis at any level. So a higher number of pro quality players are going to college knowing they have more time on the back end. Yet, at this time, the quality of coaching and the system sucks. With more and more pro quality players going to college, they leaving college with less skills than they came with. Which is why 1st and 2nd year college players with pro potential usually do very well. ( Jamie Loeb for example) yet after 2 to 3 years, skills will have diminished greatly.
It's not new news that college tennis doesn't prepare players for the pro tour. Everyone knows that. I would say most college coaches have no interest preparing players for anything other than at most, NCAA's. Most but not all. University of Florida, University of Georgia and a couple others, have placed an interest in truly developing their players, and have done a great job. ( Brianna M, Olivia J. Lauren H, Silvia G has improved greatly) yet 99% of colleges do not. Players just need to be aware before entering college, so picking the right school is crucial if they plan to do more with tennis post college.
Tennis is no way comparable to the other sports, because turning pro in tennis has many different variable that determines if a player chooses to turn pro or not. In tennis, a player can have all the pro potential in the world, but without sponsors to atleast help foot the bills, pro tennis isn't an option and college is the only option. reguardless of the talent. Something football, basketball, baseball players don't have that to worry about. If you're pro material, you will get drafted, because the other sports are TRULY team sports. Tennis is not. No draft in tennis. So there are more players with pro potential that will end uo going to college. (Sorry for the typos..in a hurry)