While driving, do you understand how the engine ECU of your car computes how much fuel to inject into the cylinder, how the ECUs distribute the power, and the braking force on individual wheels, or how your rear wheel steering calculates the turning angle of the rear wheels based on your seed and steering input?

You don't need to know most of the details how your car works in order to drive. You need much more knowledge to build one, yes, but not to drive.

There are different levels of abstractions and depending on your problem you need to understand them only up to a certain level. And different people have different problems to solve.

In most real-world problems today, the difficult part is indeed the data, not the underlying math of the activation function, loss function, or optimizer. Just Google "data-centric AI Andrew Ng" to read more on the topic from one of the most well-known people in ML.