[wolfbln]

@NFH
You may be right in theory. But most packages for "domestic" use that are offered in each EU country are valid within the own country only. Right now, there are very few "roaming" packages on the market. Still, a provider selling 1 GB for €10 domestic can go up to around €70 (10€ plus 1000*0.05ct plus tax) for the same roaming package.

I don't see any policy enforced on the provider that the same domestic package is required to be offered on EU roaming too (possibly with a surcharge of up to 5ct/MB plus tax). But your statement implies that I can use my domestic package allowance abroad too, which is mostly not true up to know. Have I missed a planned regulation, that providers are required to open their "domestic" package allowance to EU roaming?

Often a default rate per MB is the only rate offered for EU roaming. Only very few providers actually sell "roaming packages".
The DOMESTIC default rate for data can be as low as 1p per MB on Three UK, but is e.g. 24ct per MB on many European providers. This rate is absurdly high in some countries to force users into bundles.

So for EU roaming on default rate, Three UK will be only allowed to charge around 6p/MB (1p domestic + max. 5p surcharge), but many EU providers can go up to 30c/MB (24ct/MB default rate plus max. 6ct surcharge). This obviously adds up to higher prices than the current EU cap of around 23ct/MB with some providers. This new legislation can easily be circumvented by not offering "roaming packages" (or not opening their "domestic" packages to roaming), so every customer has to stay on the high default rate.

dg7feq showed the other big trap of the planned regulation: interntl. EU call charges, now capped at 0.19ct/min plus taxes on EU roaming (when calling from abroad). Normally, calling from your own country they are charged very high with many providers at €1/min or more for international calls. If we get rid of the cap and will replace it by a limits to surcharges scheme, a provider will be allowed to charge €1.06/min or more for intertl. calls which used to be capped at 0.19ct (on roaming).