How can someone be buying a home in Indiana website shows total assessed value of 0$ and tax due 0$

Call the Bartholomew County Assessor's Office at 812-379-1505 and ask them about assessment and tax abatements and exemptions.  Most assessment and tax laws are administered at the local city and county level but prescribed by state law (in this case Indiana).  An assessment of zero and tax burden of zero is very unusual.  Typically a portion of the assessment or tax would be offset by a Homestead Exemption, but not the entire amount.  Personally I believe that states and local taxing jurisdictions should be very careful about tax exemptions and abatements because such provisions increase the tax burden of those who do not qualify for exemption or abatement.