to be honest food prices in Spain are very cheap compared to here anyway, no matter whether you are in Lidl or another chain.
In relation to Germany, it may be due to the fact that both Lidl and Aldi have a huge ammount of shops there, so they are in more competition to each other than here, and they are also in big competition with other discount chains that exist in germany, which do not exist here ( I cannot remember the names of these chains but there are several which are even cheaper than Aldi and Lidl and are very widespread there). Also Germans are a lot more price-conscious that us Irish, which is why we will happily pay a lot more for the same thing and not question it. On the flip side to this, in regard to Spain, wages generally in Spain are a lot less than here, so it is bound to be the case that groceries etc are cheaper there than here ( I have found that clothes however are no longer that cheap there, but that is a different story )
Perhaps it is also a bit of a snobbish thing here . I know several people who will never admit to shopping in Lidl, but who I know shop there regularly. Silly attidute but it does exist.
I have to agree with Carpenter and Stobear. Without the entry of these to the Irish market, we would be paying a lot more than elsewhere for groceries, as Tescos, Dunnes, etc only brought down their prices due to competition from these German chains. So, okay we are paying more than in Spain , but we would be paying a lot more again if they were not here and we were still relying on the UK and Irish chains !!