Aggregators - why they exist in specific markets

Meta search and aggregation (for the purpose of this article I'm saying these two are the same thing, although some may claim there are subtle differences) have grown over the last few years to be a dominant acquisiton force in a number of important online vertical markets.

Financial services, from credit cards through to insurance, are now subject to aggressive aggregation from a handful of major players such as: compare the market, go compare and moneysupermarket.

Utilities including: gas, electricity, mobile phone tariffs and broadband access are now compared online. In fact a lot of fuss and claims are made by the market leaders in this sector that they are championing your consumer cause (without obviously stating that your business with them helps their financial cause).

And travel has its obvious aggregation in the form of meta searches for: car hire, hotels, flights, etc.

Each aggregated vertical has its specific nuances and intricacies, plus each its own referral & commission structures, but in essence the the business model is the same:
a. Collate as many similar products or services as you can
b. Provide a single interface that qualifies the visitor's choice (usually by a series of form fields common to all parties)
c. Deliver the results in a consistent and comparable manner (usually cheapest first, but also allowing the user to filter some options)

Aggregators exist because two simple facts:
1. customers do not believe that they always get the cheapest rate for all products from one supplier
2. customers do not want to spend the time completing the same form on numerous sites

But why don't aggregators exist in other markets... such as fashion or FMCG products (e.g. washing powder and chocolate bars)?

Well, for fashion products, the usual reason is that products are exclusive to the manufacturer. Therefore because the channels to market are all protected (e.g. the manufacturer has some level of control over price and/or distribution) there is no real flexibility in the price. Then (assuming the brand site has eCommerce functionality), it is then typically just as cheap for users to shop from the brand site as it from a re-seller.

For FMCG the lack of aggregation is a different one, that of convenience. Most shoppers, when looking to source FMCG products go to a grocery store or supermarket. They also assume that the shop has done some sort of price comparison with the competition, so they don't have to (although prices may only be matched for the core 'basket' of goods and other less common items are still priced to maximize profits). Although sites such as http://www.mysupermarket.co.uk have sprung up to allow web users to compare grocery and health & beauty products from the leading retailers, people still either only visit one store or use one online supermarket at a time.

The question I have is... are there any remaining markets where aggregation is possible but has yet to take off?