I do not agree with Israel's policies on the West Bank, but the issue is more complicated than I suspect you think and I encourage you to read Israeli perspectives on it.
B) Apartheid South Africa used the same excuse. That black people lived in independent bantustans who were self governing and therefor not apart of South Africa.
C) You are ignoring the fact that Israel very much controls Gaza, including every border crossing, the airspace and sea access, imposes a blockade, controls the registry, etc. Unlike apartheid South Africa, Israel does not recognize independent Palestine, let alone independent Gaza.
B) The apartheid in South Africa was based on race. By contrast the different policies in the West Bank reflect the historical and cultural context there: that it used to be part of Jordan, that the people there want to be separate from Israel, etc.
C) Israel does not control Gaza's border crossing any more than the US controls Canada's border crossing. Israel is an independent, sovereign country, so of course they get to control who goes in from Gaza. The other border gaza has is with Egypt, and Egypt has the same policies.
Pro-Palestinian rhetoric on this site goes off the rails in so many directions, and because it seems to be the majority opinion on the site, there are many more examples of off-the-rails comments from that side. But this assertion of Gaza's independence from Israel is one of the reliable off-the-rails pro-Israel sentiments I see here.
Gaza was blockaded. Israel tried to control who and what goes in and out of Gaza (to try to limit the weapons Hamas has). But Israel had no control over what the Hamas Gaza government did in Gaza, how they spent their budget, what they built, what they taught in schools, what their military was planning.
Palestinians in the occupied territories may not be Israeli citizens, but neither were the South African residents of the bantustans, so which passports the subjects of Israel holds doesn’t matter. What matters is that Israel controls most aspect of their lives and imposes different rules and condition depending on whether you are Israeli or Palestinian. However you separate the population doesn’t matter either, the fact that Israel does is all that counts.
There is a different legal system on the West Bank, true, however the Israeli settlers living there get charged in Israeli courts, and so do Palestinians, except that Palestinians get charged in a different court system, namely military court. This is a double justice system, and there is no other way of describing it. Modern liberal democracies don’t have those, only apartheid states do.
Gaza was reliant on Israel for water because Hamas not only didn't invest in infrastructure, but literally dug up water pipes to make rockets. Why the heck should Israel be responsible for providing Gaza with water, food, fuel, or electricity? Do you also believe Ukraine should provide this stuff to Russia?
It would be a "breakaway province" situation, except that:
a. Israel intentionally got all its citizens out of that place and
b. Israel had no intention of taking control and forcing Gaza to join back into Israel.
Israel mistakenly thought Hamas was transforming into a national government that is busy governing its territory.
Gaza was mostly an independent country at war with Israel and not even a little bit an autonomous province of Israel. The war could not be resolved and so it was stuck in a state where Israel thought it prevented Hamas from bringing in heavy weapons but did not want to commit to conquering a city.
I think some people thought that after Israel pulled out in 2005, and Gaza became autonomous, it would become a normal independent country, and people still treat Gaza of 2023 as if it's the Gaza of 2005.
Having control over a territory is what makes it occupied. And Israel very much has control over Gaza. The government and the legislator is one of few things which Gazans them self control, almost everything else is controlled by Israel, including the population registry, what goes in and out, etc.
> Israel mistakenly thought Hamas was transforming into a national government that is busy governing its territory.
They never thought such thing. There were regular bombing campaigns which Israelis described as “mowing the lawn” (talk about dehumanization) where the Israeli military went into Gaza—sometimes with groundtroups—including in 2008, 2012, 2014, 2018 and 2021. In 2018 the Israeli military indiscriminately shot at unarmed protestors inside Gaza. Israel always assumed Hamas to be a terrorist organization first, and an illegitimate government of Gaza second.
I think if someone is going to raise the "Gaza isn't Israel it's an independent country" argument, the facts lining up against an natural reading of that kind of statement make it incumbent on the speaker to lay out the qualifications and contingencies, rather than counting on other speakers on the thread to do it for them. It's not a thing you can just say and pretend is clear; it's more or less an extraordinary claim.
I'd entertain the argument if someone wanted to explore it in a curious fashion. But, like, it's not true. Gaza is occupied territory in the intuitive meaning of the term.