While I think it would be great if the players knew the rules, often that's impractical or even impossible.
Despite the TDA's efforts, not all poker rooms follow the same set of rules.
Some players play at multiple poker rooms. Remembering all the differences would be a challenge.
Even if all rooms followed the TDA rules, those change and it may be difficult for the average player to keep up.
Some poker rooms have different rules for cash games vs tournaments.
I once asked a floorman if they were following Robert's Rules and/or TDA rules and was told that they have their own in-house set of rules. When I asked if I could read them, I was told that they are not available for player review. WTF?
Once at another room, there was a question about a short all-in raise. The dealer asked the floor, even specifying that he heard that the management was considering changing the rule. The floor said that the rule hadn't been changed yet. Later that day, the identical situation arose and the floor ruled differently. I objected and asked when the rule got changed. The response was that that rule never changed. Then I told what happened that morning.
Bottom line, if floorpeople can't keep the rules straight, what chance does a player have? If a player asks a question about the rules, it must be answered.