ER purchase tenders are usually limited to a very small group of large Retailers/Aggregators/Brokers.
This forces small independent projects to sell via Retailers/Aggregators/Brokers.
Retailers/Aggregators/Brokers often give the misleading impression to buyers that they are project implementers by featuring independent projects on their websites that they refer to as "Our Projects". Most of the projects listed are implemented by outside parties (e.g. small independent projects) so that the Retailers/ Aggregators/Brokers are just brokering these projects.
Some Retailers/Aggregators/Brokers do start and manage their own projects but then often go on to stack buyer requests in favour of their own projects rather than those of outside developers.
Retailers/Aggregators/Brokers often aggregate blended-price-portfolios* with ERs from small independent projects in response to tenders.
Buyers often never find out what prices were actually achieved by the independent projects due to this blending and sellers (independent projects) will usually never find out what price/margin the Retailers/Aggregators/ Brokers actually achieve.
Intermediaries in other functioning markets usually have transparent or mostly-transparent commissions - e.g. real estate and stock brokers.
* Blended-price-portfolios usually involve aggregating VERs from different projects into a single 'basket' of credits and selling the entire 'basket' at a nominal single-price-per-VER (even though the prices paid to the individual projects are different to that nominal price).