How are they trivial? From my limited knowledge they are basically trying to stabilize a speculative asset using another speculative asset. To me it seems like an essentially impossible task.

Yeah. In theory they are broken.

But in practice they can work for a while.

They work by taking a collateral and splitting in two. The first part has some fixed value in an external currency. The other part is the rest. And that works as long as the rest has some value.

However here we are talking about programming errors in the implementation. And Solidity/Ethereum is really at fault.

How do you implement a contract in Ethereum where a certain thing happens the price of Ethereum drops below XXXX dollars? You can (as this is what MakerDAO and others are doing) only it is silly complex to do.

It really should not be.

Most things are simple in theory and not so simple in practice. Also just because people write programs with bugs doesn't mean the language or platform is at fault. Sorry but it sounds like you have no idea what you're talking about.

EOS tried to use on-chain Ricardian Contracts and pair that with upgradeable smart contracts in C++ with DPoS consensus so that intent-of-code could be enforced. That's pretty "real world" but most people feel it's not unstoppable enough.

Ethereum is pretty unstoppable, but unless you use a contract proxy, your contracts are immutable and bugs that can be exploited will be exploited.

Contracts need to be written in a specialized language not a general purpose language like c++.