Some players like the risk of death around every corner. They don't mind rolling new characters and joining back into a campaign. To them if there's no ultimate consequence for their actions it's all pointless.
Yet you'll find others who don't like their characters dieing unless they are OK with it. Usually as part of the story or in some other meaningful way. They don't like wasting time rolling new characters and trying to integrate back into the campaign.
Most of my players enjoy the risk and I try to live up to their expectations. I often throw at them challenges above their level because they are seasoned players, they want the risk, and that's the game we play. Another thing that keeps me honest is that I roll everything in the open. I asked the players if they wanted me to roll in secret or in the open; they said they don't want me fudging in their favor and to keep everyone honest then everyone rolls in the open. I don't use lame GM PCs or super NPCs to babysit the PCs... to me the game and story is all about the players and their characters. Their actions and the dice dictate circumstances... it's not really up to me who lives and dies. They stated their actions, they rolled the dice, and I tell them the results.
We occasionally have a player who I can tell doesn't like high risk. I try to go easier on them because I can appreciate their play style and I don't get any satisfaction out of killing characters. I try not to be too obvious about it and generally these players are more cautions anyways. They tend to survive as a function of their caution and by me easing up on them slightly.
The reason I know the expectations of my players is because we communicate. I ask them out right what kind of game they want to play. I ask them "hey, I got this really awesome scenario you guys would like.... but it's a real meat grinder... you OK with that?" which is replied with a "hell yeah!". Again; I asked them about rolling in the open because they know secret rolls = fudge... they wanted me to roll in the open. I ask them after game sessions what their favorite parts were.... I get responses like "That last battle was awesome because I ALMOST died and we barely won!" I've had characters die and nobody got mad or rage quit. They knew it was a result of their actions and were OK with it... again reaffirming the type of high risk game they enjoy. To contrast that I had one player throw a fit because they got level drained by a monster... "note to self: go easier on him or there will be drama" =P Everyone else at the table was fine with it.
I could see where a GM at a con would say "This is how I GM and if you don't like it then maybe this isn't the table for you". I mean they don't have the luxury of getting to know their players well. I assume there's other tables at the event... you don't like one? Move to another...
With regards to game systems I've also found that our more rules-lite games make people more open to higher risk because it doesn't take an entire freak'n game session to research and roll up a new character. Unlike so many other systems the rule sets and characters are so overly complicated and convoluted that unless you've committed much of it to memory you spend hours putting together a new character. Honestly we are more about role playing and enjoying a good game than debating rules or rolling up new characters.
I'll shamelessly plug Pathfinder LITE
as our game system of choice! Everything you need and nothing you don't. A simple yet robust version of the outstanding Pathfinder d20 system!