The European market is used to amphetamine. It is as cheap as £5 for a gram, and is of decent potency usually. Even if you explained to someone this "new speed" was way better most people would tell you to fuck off if you wanted £50 for a gram of meth.
The producers in Easter Europe know there is a huge market of amphetamine users in Europe, and probably have a good supply chain of precursors. To turm amp into meth requires an addition reaction using a gas chemical, which is an expensive step because everything has to be airtight.
A sudden change to meth would create massive upheaval in the usage of speed in Europe and many people would either stop using speed or end up killing themselves (1g~1.5g of amphetamine isn't unusual in a night out, that much meth is VERY dangerous in a short period of time).
Meth is gradually beginning to appear, particularly in the large cities in the UK and sometimes Ireland. Given another 10 years I imagine it'll be much more prevalant as people slowly find out about it, and experiment, but no sudden change can occur.