Why does EU have 4 different legislations prohibiting discrimination on grounds of nationality?

Question

1. Aren't these 4 separate EU legislations redundant?

2. More specifically, doesn't EU need just one of Art 18 and 45 TFEU to prohibit discrimination on grounds of nationality? "It is the constituent Treaties, the TEU and TFEU, which sit at the top of the hierarchy of norms in the EU."¹

3. Even if Art 18 and 45 TFEU don't suffice, why does EU need both a Regulation and a Directive? Reg 492/2011 overpowers Directive 2004/38. Why does EU still need Directive 2004/38?

"Regulations are binding in their entirety and directly applicable in all Member States."² "Directives differ from regulations in two important ways. They do not have to be addressed to all Member States, and they are binding as to the end to be achieved while leaving some choice as to form and method to the Member States. The ability to act through directives as well as regulations gives the EU valuable flexibility. The direct applicability of regulations means that they have to be capable of being ‘parachuted’ into the legal systems of all the Member States just as they are. Normally every ‘t’ must be crossed, and every ‘i’ must be dotted in regulations, since Member States must not tamper with them. There are, however, areas where it is difficult to devise regulations with the requisite specificity, which are suited to immediate impact in the Member States, more especially because the Member States have differing legal systems, and there are variations in the political, administrative, and social arrangements within the Member States."³

Please see my green arrows. EU Law Concentrate (2020 7 edn). pp 122-123.

Article 18 TFEU

Within the scope of application of the Treaties, and without prejudice to any special provisions contained therein, any discrimination on grounds of nationality shall be prohibited.

The European Parliament and the Council, acting in accordance with the ordinary legislative procedure, may adopt rules designed to prohibit such discrimination.

Article 45(2) TFEU

2. Such freedom of movement shall entail the abolition of any discrimination based on nationality between workers of the Member States as regards employment, remuneration and other conditions of work and employment.

Regulation 492/2011

Does anyone know which Section and Article the flow chart refers?

Directive 2004/38 Article 24

1.   Subject to such specific provisions as are expressly provided for in the Treaty and secondary law, all Union citizens residing on the basis of this Directive in the territory of the host Member State shall enjoy equal treatment with the nationals of that Member State within the scope of the Treaty. The benefit of this right shall be extended to family members who are not nationals of a Member State and who have the right of residence or permanent residence.

2.   By way of derogation from paragraph 1, the host Member State shall not be obliged to confer entitlement to social assistance during the first three months of residence or, where appropriate, the longer period provided for in Article 14(4)(b), nor shall it be obliged, prior to acquisition of the right of permanent residence, to grant maintenance aid for studies, including vocational training, consisting in student grants or student loans to persons other than workers, self-employed persons, persons who retain such status and members of their families.

¹Craig, De Burca. EU Law 7 ed 2020. pp 147-148.
² op. cit. p 144. ³ op. cit. p 144.

Answer 1

Article, regulation and directive all have different scopes and levels of details. There is no redundancy here. You create an article as a political agreement for the union, as a matter of principle.

Then you make a directive, with more details about the article and what we're trying to accomplish.

Then you make an actual regulation, which decides in most details how the principles from the articles will be followed and goals from the directive accomplished.

Think of it as hierarchy,steps on a pyramid. Not like laws of the single country which are equal, but like "Constituon=>Law=>Local Regulations=>Worker's Manuals"

Basically, every country decides how they are going to implement a directive. But you have to obey a regulation to the letter. And Article is pretty much a principle behind the directive or regulation, like state's constitution is the principle behind the laws.