It may be common, but this idea is just plain wrong.
My Oxford Writers' Dictionary from 1990 advocates using a z in such words. And so does my A Dictionary of Modern English Usage by H.W. Fowler from 1959.
The best summary of the position I have come across comes from Mike Horne:
It seems to me that in books printed in England the use of the ‘z’ overwhelmingly predominated until the Second World War, though on a far smaller scale the ‘s’ can be found used by some printing houses, even in Victorian times. Textbooks set out the correctness of using ‘z’, some of them setting out in considerable detail the rationale for use of ‘s’ or ‘z’ depending on origin. After the Second World War the ‘s’ alternative is more frequently offered as a possibility and some house style manuals (though not Oxford’s) indicate a preference for ‘s’ — not because of any suggestion that ‘z’ is wrong, mark you, but because ‘s’ had come to be tolerated and it avoided having to remember which usage is which. Recent manuals and dictionaries seem to have given up on the prescriptive use of a ‘z’, though it is usually offered as an alternative where correct.
It seems to me, summarizing, and using a ‘z’ correctly and non-Americanly, that:
- On the whole the ‘z’ alternative has nothing whatever to do with America;
- The ‘z’ is etymologically correct (where used properly);
- The ‘s’ principally came into use by those believing it (apparently wrongly) to be correct by analogy with similar words that were current in French, when in fact the English use developed in parallel and came via Latin from the Greek, retaining the ‘z’ throughout (for example 'the realization' in English compares with 'la réalisation' in French) — in some quarters during the early days of English printing French [recently the language of the Anglo-Norman aristocracy] was regarded as posh;
- The ‘s’ took hold in comparatively recent years because it was regarded as acceptable (because of the foregoing reason) and because of the hopelessness of training uneducated people correctly to grasp the correct occasion to deploy a ‘z’ or an ‘s’. Note Tillotson's House Style (below) where they opine that use of 'z' is correct but they have decided to adopt the 's' because it gives rise to less trouble...
I use s rather than z in such words because, for better or worse, a z now looks odd to British readers. But my choice has nothing to do with the fallacy that the z comes from America.
- As the use of the ‘s’ caught on, dictionaries had to follow the trend, and are now quoting it as ‘correct’. It is arguable, but dictionaries do not necessarily promote correct usage, but follow prevailing practice (which is then taken as correct, creating a spiral of decline).