Here are the basics: there are three main types of unions: industrial, craft unions (often building trades) and public sector unions--and each in turn has been targeted. Here's how:
Industrial unions. When Republicans (just a fact) gained control of the WV legislature in the wake of the 2014 elections, they moved quickly to undermine industrial unions through so-called "right to work" (RTW) legislation, which is really right to work for less.
RTW undermines the democratic process. In a free labor state, workers vote whether or not to join a union. If the majority votes yeas, all are members and are covered in the contract the union negotiates. If the majority decides they no longer want to be union members, they can have another election to de-certify the union.
With RTW, workers can continue receive the benefits of union membership--wages, benefits, hours, conditions--without paying dues, even though the union is obligated to represent them in grievances. The end result is weaker unions, which ultimately leads to worse conditions for all workers, union or non-union.
Craft unions. For many decades, construction workers were protected by a prevailing wage laws, which was designed to ensure that workers on public construction sites were paid decent wages. This was designed to protect the public against fly by night contractors that use cheap and often unskilled labor and to protect local skilled workers. Building trade unions generally offer apprenticeship programs that guarantee a trained and skilled workforce. Non-union contractors are under no such obligation.
In 2016, the Republican-led legislature (again, just a fact) repealed West Virginia's prevailing wage laws.
Public employee unions. Probably the largest group of public sector workers protected by unions or workers' associations are those in the education field, including teachers and school service personnel. In some places, public sector workers have collective bargaining rights. In WV, they don't as of know, but still advocate for members and represent them in the workplace.
Senate Bill 451 goes after them by the so-called "paycheck protection" provision, which is more like "paycheck reduction. It makes it more difficult for workers to pay dues to the organizations that represent their interests. It also adds a penalty for work stoppages.
The biggest threat, however, is that of undermining public education altogether via charter schools, education savings accounts, and privatization. Teachers in charter schools aren't required under 451 to be covered by PEIA or the teachers' retirement system. Private entities can set their own payment and standards.
Conclusion: at least they're consistent. And working people need to be just as consistent, by showing solidarity with all workers, regardless of industry or type of union or any of the many ways rulers have tried to divide us. And, let's face it, it's high time to recognize the pattern.