Giving the 10 zehuvim is described as a "קנס", a fine as a punishment for the person who took the mitzvah. It is not restitution for the mitzvah.
An example of this can be seen in the Sm"a (sk.1) and Ba'er Hetev (sk.5) who codify that if the person who stole the mitzvah does not fulfill many mitzvos, then they should not be fined as much as someone who fulfills many and yet still steals another. The fine depends on the character and behaviour of the person who stole, not on the mitzvah itself stolen or the damage done to the person who lost the mitzvah.
This is also implicit in Tosfos on Chullin 87a DH V'chaivo. Tosfos raises the possibility of direct restitution for the mitzvah which would ensure that the same reward for the mitzvah is got by the person. However, this possibility is rejected by Tosfos because it would be a different (performance of the same) mitzvah: what's implicitly at issue is that someone has committed the sin of stealing a mitzvah which must then be punished. Tosfos explains that it is not possible to make up for the value of the stolen mitzvah itself by giving back the mitzvah. What's not at issue is the loss of value from not performing the mitzvah, but the offence of stealing. The Rosh also holds like this in Chullin 6:8:1, "אלא זו מצוה אחרת היא ומצוה ראשונה אזדא לה ומעוות לא יוכל לתקון": we are not able to correct this, which excludes any possibility of determining the value of the mitzvah in order to correct it and make precise restitution for it. The damage is done and it is in the past.
The Ramban (and Rashba) on this Gemara also say that, for these purposes there are no mitzvos greater or lesser than another, but they are all equal; "וכולן שכרן זהובים שאין שמין את המצות להקל ולהחמיר אלא כולן כך שכ". This is seen in the Gemara in Bava Kamma 91b, where the same baraita is also cited and applied to a variety of different mitzvos all of which receive the same 10 zehuvim.
In short, the payment of 10 zehuvim is a fine and a kind of compensation but it is not a reimbursement for the loss of the mitzvah which cannot be rectified. It depends on the character of the thief, not on the value of the mitzvah.
Sorry if any of my language there was a bit imprecise, but I think it gets the idea across.