there are several things used to compute the credit. for the initial maximum credit both spouses must contribute. line 6 for each column would then be $2000 line 7 would be $4000. with an AGI of around $39,000, 50% of line 7 is initially allowed as a credit on line 10 ($2000). for one contributor lines 6 and 7 would be $2,000 and with the same AGI then line 10 would be $1,000. then there is line 11 which limits the credit based on tax liability.
so you are correct since only she makes a contribution. $1,000 credit with an AGI of around $39K, possibly limited by line 11.
"It seems a bit unfair". there are many provisions of the code that one could deem unfair - that favor some taxpayers over others.