I agree 100%. Tennis players are the worst sportsmen I have ever seen in any sport. I was an official for four years and the boys were especially bad. The players are much better in the other sports.
I definitely know a few parents that have allowed their kids to give up on tennis (ie. they were multiactivity kids anyway) because of the ugliness that goes on in youth tennis tourneys... moved to other activities where presumably they'd be exposed to a higher % of folks with championship life skills.
It's getting bad all over. I went to a volleyball tournament and the lack of sportspersonship was appalling. One team would throw the ball as far AWAY from their opponents as possible to force the opposing team to walk as far as possible to retrieve the ball to serve.
Let's add a bit of perspective to all of this.
In a group of 100, how many display these characteristics? Then you might want to define how frequent this group exhibits the bad behavior or under what circumstances. Now, compare that with other sports. Is it better, worse, or about the same? What I'm getting at is, you don't want to say "tennis is bad" because X% of kids (adults) exhibit bad behavior "sometimes".
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But here is what I think the problem really is. I've been a runner most of my life. When I was in high school and college, if people were using the track and not following the rules (written or "understood"), they were immediately corrected. For example, if you were walking in lanes designated for running, you were told "damn fast" to move over to the walking lanes. And when these people were told, their reaction was almost always one of shame. They would apologize (either for their ignorance or disobeying of the rules) and quickly correct their behavior. And if they didn't, management would quickly tell them to follow the rules or they would be banned from the place. No discussion. The social pressure from all others using the track made it "very uncomfortable" to break the rules (and not give a damn). It really just wasn't possible to do.
Now things are different. When I run on the track in the morning, there are rules that specifically say how the track should be used. Many people don't follow them. When I first started using this track some years ago, I corrected them (because that's how I was brought up and what I knew). And without exception, people didn't act with a sense of shame, apologize, or correct their behavior. Instead, they got angry at me and told me "you don't own the track", etc. I was surprised at first and asked management to step in and enforce their rules. I told them that it was in everybody's interest to have all participants use the track according to the rules, or it gets chaotic and dangerous. Management basically told me they weren't going to do anything and that I should just "chill out". Essentially, they don't want to offend anyone and have them leave and lose the revenue. So the behavior correction was on my end. And I've learned it is not permissible to question the behavior of individuals, and I don't.
Now you may be agreeing that rules aren't important. That I should just "chill out". That is the culture we live in. But, this general attitude will have consequences. And IMO, that is, at least partially, what is going on in tennis (and other sports). In a culture of individualism, it is very hard to get people to cooperate in group activities. Someone will always see the advantage of breaking the rules. And if they cannot be quickly and effectively corrected and forced to follow the rules, the activity simply breaks down or at least becomes less pleasant for the group as a whole. Others see someone else getting away with it and reason (quite rightly) that they had better do the same, or they will be at a disadvantage. (This is essentially "Social Contract Theory" by the way).
But hasn't there always been cheating in tennis? Haven't people always done this if they could "get away with it"? Sure. But I believe that cheating wasn't as tolerated in the past as it is now. I may be wrong, but I believe the social pressures and expectations were different. Much like my running example above, rule breakers were quickly corrected. If someone refused to comply they were dealt with, either socially by "shunning" and/or those in authority actively stepped in and made it clear that such behavior would not be tolerated. Now I think otherwise "good people" think nothing of cheating or breaking the rules "now and then". Everybody does it. And unless you can change the culture on the wide scale (which is doubtful to say the least), nothing can be done about it in tennis in particular.
The only thing you can do is narrow your group down to "like minded people" for which rules do mean something and can be enforced by social pressure and/or management (this is what joining the "right club" is all about). But in the "hurly burly" of large scale public participation sports, nothing can be done in a practical sense. And all of the rhetoric in the world won't change that.