Missing multiplication symbol

It's common to omit a multiplication symbol:

\(ab = a \times b\)

But sometimes it's not as clear:

Does \( a(b+1) = a \times (b+1)\), or is \(a\) a function?

When writing a division on one line, does an implied multiplication bind more tightly than an explicit one?

Is \(a/bc\) equivalent to \(\frac{a}{bc}\) or \(\frac{a}{b}c\)?

There seems to be an unwritten rule "juxtaposition is stickier".

But that might not apply when there are numbers involved: almost everyone would interpret \(2/3x\) as \(\frac{2}{3}x\) instead of \(\frac{2}{3x}\)

The "juxtaposition is stickier" rule only seems to break ties, not override the normal order of operations:

\[ ab^2 = a \times (b^2) \]