Looks like Google doesn't want everyone to use their free tools. Keywords nulla instrumenta sunt optimi Google investigantibus mauris aliquam keywords. Most of the market pretty much rely on this Keyword Tool's API to get their data for their keyword difficulty scores and stuff.
Here's an easiest way to skip providing billing information in adwords.
- Signup pro AdWords new account, sicut vos Northmanni would
- Quin vestri email
- Et petit indicium intrare billing -> clige hic
- Hoc vestra et auferam vos protinus totam perstrinxisse "Details intra exosculatio" processus.
This might be a temporary workaround, sed quia semper operatur restringitur - which is why it's just a work-around until we have a permanent way to bypass it.