Example of a real world smart contract? I read many but none would really work

I was reading https://blockgeeks.com/guides/smart-contracts/ and they have plenty of examples but imo they won't work in real life.

Suppose you rent an apartment from me. You can do this through the blockchain by paying in cryptocurrency. You get a receipt which is held in our virtual contract; I give you the digital entry key which comes to you by a specified date. If the key doesn’t come on time, the blockchain releases a refund. If I send the key before the rental date, the function holds it releasing both the fee and key to you and me respectively when the date arrives. The system works on the If-Then premise and is witnessed by hundreds of people, so you can expect a faultless delivery. If I give you the key, I’m sure to be paid. If you send a certain amount in bitcoins, you receive the key. The document is automatically canceled after the time, and the code cannot be interfered by either of us without the other knowing since all participants are simultaneously alerted.

Let's say I send you the wrong code and the for doesn't open, what happens? I just lost my money because the smart contract thinks I received the code and I used the apartment. Personally I'd never do this contract if I'd be the renter.

Some examples are not really clear or are too abstract.

“UPS can execute contracts that say, ‘If I receive cash on delivery at this location in a developing, emerging market, then this other [product], many, many links up the supply chain, will trigger a supplier creating a new item since the existing item was just delivered in that developing market.’” All too often, supply chains are hampered by paper-based systems, where forms have to pass through numerous channels for approval, which increases exposure to loss and fraud. The blockchain nullifies this by providing a secure, accessible digital version to all parties on the chain and automates tasks and payment.

I bet that when you deliver something you can track that you delivered that product. That can trigger a request to the manufacturer to build a new product. Why we need smart contacts and Blockchain? I can't figure out where it helps against a simple database and some script.

I don't even mention that the way it works in real life has nothing to do with this. You probably build more products based on past performance and current stock. Not on delivery... Most likely will be triggered on sale.

Let's move to the next one.

Another few examples i can't understand or too abstract.

So my question is, can you provide a real world example of a smart contract?

I have a feeling it's very very limited... For now. What do you think?