Lets parse out your examples:
- Lane pressure
I don't know what your definition of lane pressure is so if I am misinterpreting your words, I apologize but here's my definition and hopefully it matches and the explanation will help.
Pressure in LOL (to me) is forcing the enemy to choose a different strat and sacrifice something to compensate for your strat.
So for example, punishing an enemy ADC by bursting them if they get too close to trying to last hit. Or you punish them for engaging your ADC while they are farming. Or another example would be pushing up to their tower and making it more difficult to last hit by poking them but still keeping vision in the river so that the jungler has to come down to try and save the bottom tower instead of ganking other lanes with enough notice to escape a gank.
Things like that are what I consider pressure in a lane and in general on the map. I would consider things like split pushing or forcing objectives more of overall map pressure rather than specific lane pressure but I hope you get what I mean by lane pressure
Not all supports are going to put on lane pressure depending on the enemy play style, ADC play style, and jungler. For example, if you have a very low mobility ADC and no healing support, you aren't going to try and focus on exchanges with an enemy lane that has high ADC mobility and a healing support. Why would you try and put lane pressure on in a comp where you are out sustained and your ADC cannot escape as well if they get caught out badly?
It's like... if you have a Varus and a Vel Koz on the enemy team and you have a Miss Fortune and Nami on your team, your bot lane isn't going to focus on trades because you're seriously out damaged. What your lane is going to do is focus more on farming until your junlger can come down and help with a gank and put them on the defensive. Do you really expect your Nami to start going all in? No, that's just suicide.
You have to look at the overall situation before you judge someone because sometimes there's nothing you can do during lane without outside help.
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Protecting the carry
This depends on how adaptive the ADC is for me. If I see that the ADC is suicidal and does not understand that the comp was countered at champion select, there's no point in protecting the ADC. Even if you use every single summoner and spell you have, you're hard countered and you'll lose the exchange, your ADC goes in anyway? What is the point? This isn't on the support and it has everything to do with an inflexible ADC.
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Typical mage support who sits behind the carry
Some mage sups are long range and sometimes they stay behind the ADC because they can safely poke the enemy team.
Now if they're like an annie and they're standing behind you, I get the complaint. Annie has shorter range and should be a little more in your face because that stun is super important.
However, this also might be due to the ADC's play style and that if the support sees that the ADC does not follow up on good exchanges. The ADC is AAing and pushing instead of last hitting and neither of them have escapes except summoners.
Overall I guess what I'm saying is that the ADC should work in tandem with the Support. The point of the support isn't to be the ADC's slave and sacrifice themselves all the time for the ADC. The support will only do that if the ADC is worth saving. That means the ADC has to respect the support. Whether you agree with it or not, support is actually a difficult role.
The support is the one who is tasked with warding the map, despite the fact that Riot has already capped the number of wards a player puts down. If there aren't enough wards, everyone blames the support even if there are only 4 wards on the map and they're all the support's. They get blamed for not being placed in better places.
The support is also tasked with judging lane exchanges and also team fights. Knowing who to cast what spells on. Constantly casting spells on the ADC isn't always the best because if there is say someone else who is doing a better job at taking down enemies and the ADC is being super lack luster, spamming all of the support abilities to protect an ineffective ADC is pointless and actually detrimental to the team. You have to know how your spells affect your teammates and how they affect the enemy team mates. What is better to cast when? Who do you target in your lane match up?
The support has to know how to AA minions and set them up for last hits in the event the ADC is being pushed and is losing farm to the tower.
The support has to know how to freeze a lane when their ADC backs or know how and when to push and reset.
Etc...
I don't think it's fair to just dump all over the support in general because the point of the support IMO isn't to cater to the ADC, but to cater to the team.