I don't think it's gotten any easier to verify that something was actually persisted to disk though.
The hard part has always been verifying that the data is actually persisted to the hardware. And the number of layers between you and the physical storage has increased not decreased. And the number of those layers with a tendency to lie to you has increased not decreased.
For some systems it's not considered to be persisted until it's been written to n+1 physical media for exactly these reasons. The os could be lying to you by buffering the write, the driver software for the disk could be lying to you as well by buffering the data. Even the physical hardware could be lying to you by buffering the write.
In many ways writing may have gotten more reliable but verifying the write has gotten way harder.
The hard part has always been verifying that the data is actually persisted to the hardware. And the number of layers between you and the physical storage has increased not decreased. And the number of those layers with a tendency to lie to you has increased not decreased.
For some systems it's not considered to be persisted until it's been written to n+1 physical media for exactly these reasons. The os could be lying to you by buffering the write, the driver software for the disk could be lying to you as well by buffering the data. Even the physical hardware could be lying to you by buffering the write.
In many ways writing may have gotten more reliable but verifying the write has gotten way harder.