Normally the builder's mortgage the land and entire saleable area to the bank for financing the project.
As and when there is a buyer there will be a tri-partiate agreement between the buyer, the bank and the builder. Once the sale agreement is done, the buyer will be getting a property from any lien or mortgage held by the bank which has financed the builder. Typically in such tri-partiate agreements, banks will release money only to the builder only when a particular phase of project is complete.
The Real Estate (Regulation and Development) Bill 2016 which has now been passed by parliament and assented to by the President, precisely addresses all the concerns you have raised in your query.
The Bill seeks to protect the interest of the home buyers by enhancing transparency and fixing the accountability of developers, brokers and consumers.
No longer can the builder run away taking money sanctioned by the banker and the banker also unlike earlier times cannot disburse money in full and wait for the builder to complete his commitments. moreso in case of buyers, they do not need to be apprehensive of making payment and waiting for builder to deliver the property as per his whims and fancies.
With the new law, the buyer, builder and banker have well defined responsibilities and there is also a monitoring and penalty mechanism in place that will act as a deterrent to all players.
so no need to worry henceforth.