Why do the European leagues play such small schedules. Most countries play fewer than 30 games with some below 20. Even Netherlands and Italy have short schedules compared to American professional leagues. Why?

The European Leagues are not 100% professional Leagues. The players either work or still go to some kind of school (except some foreign players). Most of the countries only play on the weekend. Another problem is that most fields do not have lights to play evening games during the week.

Besides the reasons already menioned many of the Northern European Countries have weather less than ideal for baseball, so the seasons cannot start to early and cannot end to late because it gets to cold and dark, so really you can only play in the summer.

Besides not having lights, the distances between the teams can sometimes be pretty big. And since the leagues are not proffessional peopla have jobs or studies to attend to during the day so they cannot travel early enough to get a game in in the evening (specially if there is no lights).

Also in many countries the cost associated with a lot fo traveling gets to high, since many of the clubs have very little money. Also in the smaller leagues there just isn't enough pitching to go around for too many games a week as well.

Fact there are so few games in countries like Slovenia, is, besides there ar only a handful of clubs ofcourse, is the lack of available play days. Summer time is limited due to vacations, weather in spring is lousy, and fall is playoffs time. I'm guessing most of the players wouldn't mind playing during the week, even after work, but there are no playfields equipped with lights. Last reason would also probably be a shortage of pitchers, since an average club in Slovenia has a rotation of a bout two, three starters with more utility players as relievers.