Few people are probably aware that the national flags of many countries are not, strictly speaking, national flags. There is no law, for example, that designates the Union Jack as the national flag of the U.K. In most countries, the national flag and national anthem are defined, as such, by custom rather than legislation.
No government can realistically compel its citizens to "respect" its flag, though people with nationalist ideals often believe they should be compelled to observe certain rites, like standing up when the flag is raised and singing the national anthem when it's played. Such compulsion is inherently antidemocratic and potentially tyrannical, which is why elected governments are hesitant about legally defining flags and anthems.
In 1999, the Liberal Democratic Party got the Diet to pass a law making the Hinomaru the national flag (kokki) and "Kimigayo" the national anthem (kokka) of Japan. Many citizens were concerned, given that both are holdovers from Japan's imperialist past. The LDP said that there was nothing to fear because the new law was only a recognition of the flag and the song.