Because they are proper names that define each day of the week. No other set of words can do that.
Yes, it is common practice to use capitals when writing "Good Afternoon" and "Good Morning" as they are considered as greetings.
The days of the week are common nouns in French. They are not capitalized and they take an "s" as their plural mark (je vais à l'école tous les lundis).
what planets did the romans use to name the days of the week
When used in a general sense use small letters. However, if you are writing about a named camp, use capitals, for example: Dachau Concentration Camp.
By writing letters
If showing a day's possession, yes. (e.g. Tuesday's child) If pluralizing a day of the week, no. (e.g. two Mondays)
People worked six or seven days a week.
5 days a week can take the sauna about 15 to 20 minites per day
To keep up with dates and days of the week
Not on the days as such. The song is quite old and 'traditional' so it is probably out of copyright. Please use capitals if you are refering to a title, it helps avoid confusion.
Last week I took a few days of work and visited my friends in Manchester.
dose colosseum use three kinds of greel capitals?