Most Americans are at least familiar with the nominating process of the Old Parties, called "primaries", but that's not the only method for a political party's members to nominate a candidate for office; there is also a "nomination by convention" process. This is the same process used by the Old Parties on a national level (often televised during the summer months of election years), but many of the third parties (including the Libertarian Party and the Green Party) use this method at the state and local level. My own nomination was secured using this method in mid-March.
However, after the 2018 mid-term elections, the Republicans in the Texas legislature appeared to be intimidated by -- and afraid of -- the "blue wave" that swept through the state. Believing that third-party or independent candidates will steal away votes from their candidates in 2020, they passed a law that basically taxes any third-party or independent candidate to appear on the general election ballot. The law specifically exempts any candidate whose nomination was achieved through a primary. Since only the Democrats and Republicans nominate their candidates by primary, they don't have to pay the filing fee/tax -- but everyone else does.
"Scheming demons dressed in kingly guise beating down the multitude and scoffing at the wise."
Typically, the funds received for ballot access are used to help fund the primary campaigns of the Old Party candidates. Since third-party and independent candidates do not participate in the primaries, those of us who stand as third-party or independent candidates now pay twice for the Old Party candidates' nominations; once as a tax payer, and again as a third-party or independent candidate.
By passing this law, what the Republicans in the Texas legislature are telling Texans is that the Texas voter is required to choose ONLY a candidate from either of the Old Parties, even if the positions of either of the parties' candidates align with the voter's interests. Someone once equated this as "You can drink anything you want as long as it's Coke or Pepsi. You can eat anywhere you want as long is it's McDonalds or Burger King".
"Hypocrites are slandering the sacred halls of truth. Ancient nobles showering their bitterness on youth."
By restricting ballot access as they have, even the voters themselves are also not allowed to say -- or to even suggest -- that they might want to vote for a candidate whose views might happen to align with theirs. Instead, in order to exercise your right to vote, you (the voter) are required to re-align your views to fit within the limitations that the Old Parties have set.
How is this not "pay-to-play"?
Note: A Temporary Injunction was issued on 02-Dec-2019 (one week before the filing deadline) restraining Texas Secretary of State Ruth Hughs and Harris County from enforcing filing fees against third party candidates. An article on that story is linked here: https://www.amarillopioneer.com/blog/2019/12/3/texas-libertarians-win-temporary-injunction-on-ballot-filing-fees
Update: On 23-Jun-2020, the case Dikeman v Hughs goes for oral arguments in the appeal by the Texas State Attorney General (Hughs) to
- overturn the temporary injunction of 02-Dec-2019 declaring the new ballot access filing fees on third-party candidates unconstitutional, and
- claim that Texas state law supersedes 11th District Court law, therefore the state cannot be sued or held accountable by the district court.
(Warning! It's written in 'legalese')