Skitty, you're mistaking personal responsibility for legal responsibility, personal injury for property damage, extrapolating a pattern without making sure it is safe to do so, and comparing unlike circumstances in general.
- Personal responsibility appeals to ethics and morality, while legal responsibility pertains to the laws or rules governing the situation. The former is of a far greater scope than the latter. Simply put, personal freedoms allow for people to be ethically or morally "wrong" to a degree. Just as important, ethics and morality often have to deal with concepts that are vague or actually impossible to know beyond a reasonable doubt; in short you'd have to be "God". If that sounds bizarre, tell me how easy is it to know exactly how much damage to the card was excessive? What might have been there before hand, and how much of the damage done was "acceptable" for regular TCG play?
- Both actual rules and laws, as well as perceived "ethical" behavior with respect to personal injuries are different than with property damage, because in all honesty they are different. Damaging one's person is at one more serious (you may kill or at least irreparably damage them) and less (accidentally scratching a car versus accidentally scratching a person's skin, the latter can usually heal up on its own in a few days with no long term problems).
- Scale of the damage is also a factor: again laws and ethics are different. Some ethical systems claim that ultimately any "wrong" is ultimately equal in "wrongness", though from a human perspective we usually look at how much damage was done and how hard the wrong was to enact. Bending a trading card is easy, so even though said card might be expensive at the time its future worth is always in question: could be more, could be less. This is unlike personal injury, where unusual circumstances are easier to take into account: broken arm on someone in normal health versus a broken arm on someone for whom it may never properly heal due to already compromised health. We punish murder more than serious injury and serious injury more than minor injury.
- In most places, just because pattern exists in laws, damage, and compensation, it does not apply universally. The most obvious example would be the concept of "minors": a child is rarely punished the same as an adult. We have small claims courts for damages that are below a certain price range because it just isn't conducive to the justice system to treat the smaller injuries with the same scrutiny as the larger.
- Perhaps the most important is Pokemon TCG tournaments are a competition where you know going into it that your opponent will be forced to handle, somewhat roughly, your property. Your two examples were lapses in safe behavior. I can present a counter example of how injuries that occur during sporting events require gross incompetence or obvious, malicious intent to be treated as the same kinds of injury to person or property would outside of a game. Additionally it can be hard to see how much of your own actions contributed to the problem.
I can't say I am completely happy with my wording, but that's the basics.
If I damage a card of my opponent's through negligence, it is my personal but not legal responsibility to replace it. Shuffling and damaging a card is not the same as carelessly spilling soda on it.
To give you an idea, here is a scenario where personal responsibility isn't so obvious:
At the beginning of the game, one player requests that they both use a legal coin for the coin flips required for the game. This coin is made of metal, but again meets all legal requirements. The other player prefers using dice (again, perfectly legal dice). Assuming the second player acquiesces to the first, should the act of tossing the coin damage either player's cards, who is responsible for that damage? Yes, another assumption, that the manner in which the coin tossed was legal. I dislike so many assumptions but in this case such assumptions are "details" important to the scenario.
So under these circumstances, is it the player who tosses the coin when it does damage who bears responsibility (personal and/or legal) for any damage done to the cards, the first player for insisting the coin be used, or the second for agreeing to use the coin? Or perhaps neither of them, given the ground rules of the game as I understand them.