One thing that pains me about this kind of zoo of problems is that people often have the takeaway, "floating point is full of unknowable, random errors, never use floating point, you will never understand it."

Floating point is amazingly useful! There's a reason why it's implemented in hardware in all modern computers and why every programming language has a built-in type for floats. You should use it! And you should understand that most of its limitations are an inherent mathematical and fundamental limitation, it is logically impossible to do better on most of its limitations:

1. Numerical error is a fact of life, you can only delay it or move it to another part of your computation, but you cannot get rid of it.

2. You cannot avoid working with very small or very large things because your users are going to try, and floating point or not, you'd better have a plan ready.

3. You might not like that floats are in binary, which makes decimal arithmetic look weird. But doing decimal arithmetic does not get rid of numerical error, see point 1 (and binary arithmetic thinks your decimal arithmetic looks weird too).

But sure, don't use floats for ID numbers, that's always a problem. In fact, don't use bigints either, nor any other arithmetic type for something you won't be doing arithmetic on.