According to this source, the number of infringements of the "pivot countries" (France and Germany) are significantly larger than those of the newcomers such as Romania and Bulgaria.
- DE = 55 (entered EU in 1958)
- FR = 49 (entered EU in 1958)
as opposed to
- RO = 23 (entered EU in 2007)
- BG = 17 (entered EU in 2007)
The same seem to be true for related KPIs such as duration of infringement proceedings and time taken to comply.
This is counter-intuitive, as newcomers are expected to adapt much harder to the "ground-rules" than the old countries (who actually started the Union).
Question: How come that the most important countries in European Union have the largest number of pending infringements?
Note: The Commission may start ‘infringement proceedings’ if it considers that e.g. a Member State has not transposed an EU directive correctly or on time, or is applying single market rules incorrectly. Infringement proceedings only start when the Commission sends a ‘letter of formal notice’ to the Member State in question.
[EDIT] More details for non-European users (as requested in comment)
As indicated in the provided source, an infringement is a procedure started by European Commission against a country that does not apply a directive (partially or not at all):
The Commission may start ‘infringement proceedings’ if it considers that e.g. a Member State has not transposed an EU directive correctly or on time, or is applying single market rules incorrectly. Infringement proceedings only start when the Commission sends a ‘letter of formal notice’ to the Member State in question.
Several examples of such procedures can be found here. An actual example is illustrated below:
26/11/2014, MEMO/14/2130, Taxation: Commission asks ROMANIA to stop the discriminatory tax treatment of non- resident individuals receiving income from Romania Case No 2009/2134
16/10/2014, MEMO/14/589, Taxation: Commission asks ROMANIA to stop the discriminatory tax treatment of foreign legal entities Case No 2009/4343 Proceedings closed on 19/11/2015 (Romania changed its legislation)
"Why you expect newcomers to have bigger problems?" (from comment)
According to this reference, Romania si Bulgaria were admitted easier than some expected. For both countries it still applies what we call MVC for justice (quite big problem in Romania, a very big problem in Bulgaria).
Intuitively, newcomers should have more problems due to communist background: many people simply do not understand the separation of powers, the free market and other concepts related to liberal democracy. Also corruption is still endemic (they even tried to facilitate corruption by changing the law).