NBER: We study a unique quasi-experiment in Austria, where compulsory voting laws are changed across Austria’s nine states at different times. Analyzing state and national elections from 1949-2010, we show that compulsory voting laws with weakly enforced fines increase turnout by roughly 10 percentage points. However, we find no evidence that this change in turnout affected government spending patterns (in levels or composition) or electoral outcomes. Individual-level data on turnout and political preferences suggest these results occur because individuals swayed to vote due to compulsory voting are more likely to be non-partisan, have low interest in politics, and be uninformed.
In other words, all mandatory voting did was add noise to the system and as such probably made everyone worse off including the new voters.