Not just a US thing. It is very difficult to repeal legislation once its on the statute books.
Often times when an Act is past, the Government has to setup entities to implement it. Those entities need money to run, have to hire people to, make rules under powers granted vide the legislation. Once that is done, then the only practical way for the parent legislation to die is for there to be a new legislation on the same topic.
For instance the Companies Director Responsibility Act 1975*. Which made it a crime for a Director of a Company to append his signature to an account statement which he knows or reasonably suspects to have been incorrect.
You then setup under the Act an office called the Director’s Disciplinary Board which investigates and hears cases, passes fines (which can be appealed to the Courts). All that takes money and effort to setup. Once its there, very difficult to abolish. The only way reasonably is when the Government moderises the law and passes the Company Director Act of 2005 which increases the boards powers and increases its authority, that Act could concievably repeal the previous Act.
*Ficticious
Well, it’s equally difficult because congress normally uses the same process for both. But you’re right, the Founders set up the system to be inherently favorable to the status quo: in order to change the status quo you need a majority in the House, 60 votes in the Senate (which used to be 67, and even higher before that) and either the President’s agreement or enough votes to override his veto.
I was talking more in terms of the public though. The majority of the public were opposed to this bill because its unpopular elements: savings in Medicare, the individual mandate, the extra government oversight. But now that it’s passed, according to yesterday’s Gallup poll, a majority of people oppose repealing it because that would involve re-opening the doughnut hole and reinstating discrimination based on pre-existing conditions. A number of Republicans who fiercely opposed the bill, like Giuliani and Brown, have said they do not want to repeal it now it’s passed because they don’t want to be seen repealing those positive provisions.
No, it is equally difficult, in terms of how the Constitution works, to pass and repeal legislation. A repeal is simply a new law that says “that law isn’t a law anymore.” So it’s the exact same process.
That said, it is often politically difficult to repeal legislation, for all the reasons mentioned in this thread so far. But it does happen from time to time. It’s probably very unlikely to happen in the case of an entitlement program.