BitLocker encryption is optional on Windows devices. Moreover, many budget-oriented tablets (such as those equipped with Intel Z3735 and 1 GB RAM) lack TPM (Trusted Platform Module) support, which makes the use of BitLocker complicated on such devices. By default, BitLocker encryption is not enabled in Windows 8.x, and is only activated when (and if) the user signs in to their Windows 8 machine with their Microsoft Account (as opposed to using a local Windows account). If you are using a Surface RT/2 with a Microsoft account and admin rights then Bitlocker (or Device Encryption) was automatically turned on for you the first time you logged in.
If enabled, BitLocker encryption will effectively prevent an investigator from accessing the content of the device - even if booting from a recovery drive.