Yes, it's true. Moreton isn't the only 'single-street' place in Wirral; there's only one in West Kirby as well, De Grouchy Street. According to the local Land & Property Gazeteer there are also plenty of areas that have no 'streets' at all, such as Prenton, Upton, Greasby, Heswall, Pensby, Irby, etc. The reason is probably that historically in the north-west the word street is closely associated with working-class housing in built-up areas such as cities, and industrial towns and villages, whereas until the 20th century most of Wirral was predominantly rural in character. This distinction has subsequently been preserved, perhaps subconsciously, by those responsible for coming up with the names for roads in areas of new development in Wirral. Market towns also traditionally had a High Street as well, but there are only two of those in Wirral, in Neston and Bromborough.