What happens next is human nature at work: happy customers do as they are asked - and post their review to whatever reviews site the business has chosen. Less happy customers 'rebel' and post to Google.
It is probably best illustrated with real-life examples (we are using estate agency here, because the deflection is most marked with them, but the principle applies across the board)...
Here is one that is rapidly attaining mythical status:
If you look closely (and how many searchers do that these days?) you will see that this business is rated 4.7 (or 4.8) out of 5 on an - unspecified - reviews site (it is actually allAgents.co.uk). BUT 1.0 on Google - which is not only displaying that score in the business's header, but prominently displaying it again when the potential customer scrolls down and reinforcing the negative impression with both rich snippets and the reviews themselves.
What we have here is an example of three of the business's dissatisfied customers completely dominating the impression of that business in search.
Why has this happened? What follows is an educated guess - but a highly educated guess nonetheless. Bradleys joined allAgents.co.uk way back at the end of 2012 - long before Google reviews were a viable solution for businesses. They put a massive effort into becoming the dominant business in their local area on that site - and have succeeded in spades.
Then Google came along. What should have happened then? Well, at some stage Bradleys should have realised that they were travelling on a barge on a canal and 'jumped ship' (excuse the mixed metaphor) to the train/railway that is Google.
The same search, but this time on desktop (less than 30% of search these days): the reviews site is showing, but Google is a) so much more prominent and b) has name/brand awareness out of all proportion to the reviews site (note: both scores under 'Reviews from the web' in the Google knowledge panel are derived from the reviews site; the disparity is caused by a time-lag in Google retrieving the score from the business's own website).
Why didn't they/haven't they? We don't know, but we guess (again) that there is a marked reluctance among management and staff to abandon a solution that they have put so much effort into, combined with loyalty to a business relationship that has lasted over five years. One thing is absolutely certain: our advice would be to refocus all their efforts on Google.
Another business and another reviews site...
...and on Google?
...and, just for good measure (and to show that we are not picking on any one site)...
So why do businesses continue to use reviews sites?
The reasons are many and various, but none of them are valid in 2018...
- the aforementioned loyalty; and we often hear 'but we've put in so much effort'
- 'advantages' promoted by the sites - notably 'stars in search' and moderation of negative reviews (not always complaint with CMA regulations)
- awards - estate agents are particularly partial to awards, and both allAgents (with their own) and Feefo (with their tie-up with the ESTAS) play that card
- contracts - a business should never sign up to a reviews solution that ties them in to any contract period, for whatever reason
And the final clincher? Reviews sites have sales forces and Google doesn't!