External Catering - Commission?

This practice is not widespread, also venues that operate like this - one could ask if you can trust any of the other suppliers on their list, photographers etc. You could question do they recommend them because they know they are good and reliable or are the suppliers only on that list because they pay to be there.

If you have signed a contract with your venue then I would check if there is a clause that sates you can find your own supplier but there will be a commission surcharge to your supplier. In all fairness the venue can do it (not that this is right), as the charge is to the 3rd party so not a contractual breech in terms of your contract but is your suppliers choice to pass on to you, which I can see why they would. If this has not been mentioned at the time you signed then you could have a case of legal frustration and negotiate with them. If by paying this charge it means your supplier will be on their preferred list then it is a potential revenue maker for them so the charge acts as an intro fee, if it is a one off charge whilst not on their list then it could be a good thing for your supplier to pay it for potential future business, you could maybe explain it to them that way as it is not reasonable for you to pay the cost for their potential future business. I would ask your supplier to ask them what the fee gives them in terms of exposure, if the expectation is they pay this every time they are used even if they are on the preferred list then this practice is essentially profiteering which is illegal, the venue need to confirm what the fee gives the supplier. I hope you get it sorted

It very much sounds to me that every time the supplier works there they will be effectively charged 10%. If I was told this by a perspective wedding couple when they enquired about my services then I would say I am sorry but I will not be willing to shoot at that venue unless the couple pay the extra. The venue basically want me to pay them over £100 for the "privilege" photographing MY wedding couple at that venue. Anyone who is willing to soak up that 10% seems to me to be desperate for the work and sounds like a supplier that you should be avoiding.

As for any potential gain I may receive from exposure at that venue is non existent - I loose £100 every time I shoot there.