Why does Table 4 use a lower value for ATSC max_splice_rate than MPEGs MP@HL?
The max_splice_rate in MPEG is the ratio of the maximum vbv_buffer_size for that profile/level to the splice_decoding_delay for the given splice_type. ATSC specifies a smaller vbv_buffer size than Main@High, but that only lowers the max_splice_rate from 38 to 31 Mbps. But today it is rather difficult to meet even this lower max_splice_rate constraint with a 19.39 Mbps stream, and since almost no one initially will be using a rate higher than 19.39, the max_splice_rate has been chosen to maximize the picture quality for the most users.