There's different types of difficulty, and dismissing another Job's complexities and not certain aspects of your own is pretty unfair. Writing this, I realized that SAM's difficulty can be summed up by simply saying there's a lot of damage available to the Job, but it's extremely easy to leave on the table. It's not entirely difficult to maximize, but there's a lot of it to be done, and doing things incorrectly means you're either pushing your big hits further back, or you're flat out leaving potency sitting. So yes, deciding how to deal the high damage is crucial. And to criticize other things you said?
GL is a passive buff that's given by doing combo finishers, even if you're doing the incorrect combo or rotation. BoTD at this point is pretty much the same, and some DRG consider it braindead until you hit LoTD, because all it calls for is hitting buttons in a sequence. Same with BLM, because you can't even really lose Enochian unless you want to (transposition actually helps). GL is shorter, but it's been made easier with Form Shift, Shoulder Tackle for quickly getting back to the boss after mechanics, the buff application change in 3.xx, the extended timer (almost certainly required for Riddle of Fire), and Riddle of Earth. At this point, MNK has the tools for the majority of scenarios where they'd lose GL, and all it comes down to is, "Hit these buttons- Keep GL".
SAM doesn't have an upkeep mechanic, so that's a fair judgement, and in that sense alone, GL remains a (very) slight step above SAM in difficulty. However, as all Sen are tied to combos, the difficulty becomes not overlapping/stacking a Sen you already have. This concept is functionally the same as not wanting to complete combos on WAR with maxed Wrath/Abandon stacks. So actually, Sen not dropping off is actually more of a detriment. You lose Sen/damage in a different way than losing GL. You lose damage because you need to refresh your buffs, but you also end up stacking Sen that's already active if you don't have Hagakure up. So yes, they get hurt just as badly by ill-timed mechanics.
This concept becomes even harder on boss jumps. You'll almost certainly have a surplus of Kenki, so your Job is to do your normal opener, but you have to switch around a ton of abilities based on how much Sen, AND Kenki you have. In Susano, sometimes I have max Kenki on phase change, sometimes I don't. Sometimes I phase with the damage buff up, sometimes with the speed buff. Sometimes I have 1 Sen, sometimes 2, sometimes 3. You have to think about how you want to use these to the maximum damage benefit, because it's VERY easy to WASTE damage on the Job, in these scenarios (which come up often). And whatever choice you roll with, it will change the timing of buffs, the opener, and even the following rotation in some scenarios.
The buff timers are long, but it's because you have situations in which you have to cycle two, 3-hit combos, into an Iaijutsu, into another GCD before getting back to it. That scenario comes very rarely, but it does take your timer to it's limit. Most times you're clipping them, so it doesn't matter that they have long timers and becomes a moot point. But during mechanics, they can become extremely tight, again, because of Sen not falling off, and trying to cycle through Sen in the correct way you need to based on buff priority, AND Iaijutsu priority.
I'm not sure ANY Job, even MNK, needs to sacrifice damage to prime hard hitting moves, unless you're talking about Tornado Kick. And if you ARE talking about Tornado Kick, they clearly have an intention for when that's to be used, even if the intent is lame.
You're greatly exaggerating the 'effort' comparisons. It is not the same kind of effort, nobody should argue that. But it is effort all the same. I could call BRD easy because they don't have positionals or requirements to stay in close range of the boss. It isn't a lie that they don't have positionals, but they have different things to worry about, making them difficult in their own way. Same goes for every Job, I've noticed. So yes, SAM are in fact putting in work, you're just downplaying it because it isn't the kind you do.