It's found that the gravity Left/Right are deprecated, a developer should use Start/End. For the text to scroll it needs a "wrap_content" set to its width, additionally the textDirection needs to be set to RTL. For unknown reasons, textDirection did not work programmatically, but worked in the xml.
This code works well on all API versions of android.
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="end"
android:textDirection="rtl"
android:scrollHorizontally="true"
android:scrollbars="horizontal"
android:singleLine="true"
android:ellipsize="none"
android:text="@string/txt_start"
android:textAppearance="?android:attr/textAppearanceLarge" />