From this blog post
Did you know, out of all the varied faiths existing in the country, ONLY Hindu religious establishments have to share their earnings with the state? This because of the Hindu Religious & Charitable Endowment Act 1951 under which a State govt. gets the right to audit temple funds, appoint archaks (priests), set up a committee to monitor temple affairs as well as appoint an Endowment Commissioner to look after the donations given to the temples.
This is an example of another damaging legacy of the British Raj which we have failed to correct in the 65+ years of our independence. This would be another thing to fix before we worry about the Ram mandir, as I said in another post.
There is a also a petition to correct the situation.