As other commenters have pointed out below, the issue the ACCC took was not that they didn't request reviews from all customers, but rather that they specifically and actively excluded people who they suspected might have had bad experiences from a program where otherwise all other customers were included.
From the ruling [0]:
On a weekly basis, Meriton provided TripAdvisor with the email addresses of guests who had stayed at its properties and TripAdvisor sent email invitations to these guests to post a review. However, rather than sending TripAdvisor the email addresses of all guests who had stayed at its properties (other than those who had requested that their details not be provided), Meriton adopted the following two practices:
(a) The first practice was to add the letters “MSA” (which stand for Meriton Serviced Apartments) to the front of the email addresses of certain guests. This rendered the email address invalid. This practice was applied to guests who had made a complaint or were otherwise considered likely to have had a negative experience at a Meriton property. I will refer to this practice as the MSA-masking practice.
(b) The second practice was to withhold from TripAdvisor the email addresses of all the guests who had stayed at a property during a period of time when there had been a major service disruption (such as the lifts not working, no hot water, etc). I will refer to this practice as the bulk withholding practice.
From the ruling [0]:
On a weekly basis, Meriton provided TripAdvisor with the email addresses of guests who had stayed at its properties and TripAdvisor sent email invitations to these guests to post a review. However, rather than sending TripAdvisor the email addresses of all guests who had stayed at its properties (other than those who had requested that their details not be provided), Meriton adopted the following two practices:
(a) The first practice was to add the letters “MSA” (which stand for Meriton Serviced Apartments) to the front of the email addresses of certain guests. This rendered the email address invalid. This practice was applied to guests who had made a complaint or were otherwise considered likely to have had a negative experience at a Meriton property. I will refer to this practice as the MSA-masking practice.
(b) The second practice was to withhold from TripAdvisor the email addresses of all the guests who had stayed at a property during a period of time when there had been a major service disruption (such as the lifts not working, no hot water, etc). I will refer to this practice as the bulk withholding practice.
[0] http://www.austlii.edu.au/cgi-bin/viewdoc/au/cases/cth/FCA/2...