What you are noting is that there is a very large cultural gulf between Math SE and Physics SE.
In the early days of the site, the Physics SE community decided that they would not answer homework (or homework-style) questions, and adopted a hard line policy against such questions. As such, homework questions on Physics SE are typically closed quickly.
By contrast, the community at Math SE did not implement any such policy, and perhaps tacitly encouraged the asking of homework questions (there used to be homework tag, even). It was only later (maybe four or five years ago—not long before I established an account here, so my history is second-hand) that the community here noticed that this policy caused problems (e.g. large numbers of low-quality questions, a reputation in the wider world as a homework mill, etc). However, by the time the problem was observed, the culture here was fairly well set, and there are vocal groups which support homework-style questions, as well as vocal groups in opposition.
The current policy is that questions asked on Math SE must provide context. This represents a compromise position between the two camps hinted at above. However, the Math SE is made up of a diverse bunch of folk, and not everyone who participates is (1) aware of the policy, or (2) in agreement with the policy. Moreover, hundreds of questions are asked every day and there are only a relatively small number of users who are willing to take the time to work on quality control. As such, a lot of low-quality homework-style questions end up getting asked (and rewarded) here.
To answer the lede question: no, Math SE is not meant to be a homework site, but the culture here is more permissive towards homework questions (often to the detriment of site quality).
A concluding thought: I think that you are over-generalizing when you say
Since I have a problem with the Physicists site, I decided to ask the same questions on the Mathematicians site and the reaction is quite different I have a lot negative score with Physicists and almost exclusively positive feedback from mathematicians.
You are getting negative feedback on Physics SE, and positive feedback on Math SE. This does not mean that you are getting negative feedback from physicists, or positive feedback from mathematicians. It only means that you are getting feedback from the members of these communities who vote, most of whom are likely neither physicists nor mathematicians.
