Millions, billions, trillions and the SI prefixes

The SI prefixes are rarely adopted by the news media for expressing large quantities, typically sums of money, populations and geological time (quantities of widespread discussion!). Journalists worldwide abbreviate thousand as 'K' or 'k', million as 'M' or 'm', US billion as 'B' or 'b', and US trillion as 'T' or 't'.

The Australian Government Style Guide (AGPS 2006, p.174) recommends:

"Milllions of dollars may be expressed by placing 'm' (unspaced and without a full-stop) after the number (e.g. $2.751m)"

A web search of news websites shows that the most common currency abbreviations are:
thousand k = 52% (K = 48%)
million m =77% (M = 23%)
billion B = 58% (b = 42%)
trillion T = 88% (t = 12%)

It looks like the AGPS meme has prevailed with 'm'; but it's a bad idea - 'm' is the SI symbol for 'metre'. Why would we want to invent another four abbreviations, when we have four perfectly-good internationally-agreed prefix symbols (k , M, G, T)? Thankfully, the AGPS gives no guide to currency abbreviations for thousands, billions and trillions.
Luckily, the abbreviations 'k', 'M' and 'T' match the SI prefix symbols for thousand, million and trillion, so at least headlines which state TV audience of 65M or 2008 US budget of $2.9T are aligned with the SI.

It's unlikely that media articles will ever use the agreed international representation of a physical quantity (i.e. the product of a number and a quantity, e.g. '40 G$') to represent a sum of money, so perhaps the CGPM should surrender to common usage, and replace G with B ('biga') as the prefix for 10⁹. Then the headlines of the $40B Enron trial will also align with the SI!