I just purchased property this year, Why is the name(s) of the prior owner still on the tax bill?

M.G.L. Section 59-11 Real Estate

Taxes on Real Estate shall be assessed in the Town where it lies, to the person who is the owner on January first, and the person appearing of record.

Property tax assessments are billed on a fiscal year basis, from July 1 to June 30, with an effective date of the previous January 1.  This means at the owner as of January 1 should legally appear on the tax bill.