That's quite true Paullow, fair point - I was taking into account the men's tournaments as well - but yes I didn't realise that on the women's side that there was as few as that but then again the likes of the Czech Republic, Romania have only one regular tour event where as the Ukraine, Serbia, Croatia, Belarus, Latvia Belgium (unless you count Strasbourg) don't have any at all. Plus Ponchet also had a wc into the aus open in 2018 as well as last year's French, so she has already had good opportunities to prove herself so as harsh as it may sound I would not have too much sympathy for her if she wasn't able to play Strasbourg and have to earn her place at RG.
Some fair points there as well and Ponchet, and other 'leading' players from US, Aus and France (outside of the main draw cut) do benefit from that reciprocal agreement and certainly more than players from those other European countries you mention. This next point isn't necessarily aimed at you, more generally, but what about the advantages for the Chinese players? It doesn't host a slam, but it has a PM, P5, a new P from next year and about 8 internationals, plus the WTA finals, and Elite trophy - much more than France, and in fact more than any other country, including the USA.
Wang Qiang's Chinese run last year was absolutely amazing and you could say it's what WCs are all about, but if she had the South Korea or Thailand flag next to her name instead then she certainly wouldn't be anywhere near 16th in the world right now and getting byes and seeding into the likes of Miami, IW, Rome and Madrid, simply because she wouldn't have had the opportunity to do what she did last Autumn.
She got an expected MDWC into Wuhan P5 last year due to her birth place, fair enough, but for overseas players with her ranking at the time, it would have been qualifying at best. She was playing great until she was worn out by the time she faced Kontaveit in the semi finals and retired - imagine what she would have been like with 2 or 3 extra qualifying matches prior to that... Maria Sakkari also reached the Wuhan SF the year before, but she wasn't allowed to play Beijing PM the following week as the semi final clashed with Beijing quals - where was her Beijing MDWC there (for those referencing Teichmann and Bacsinszky, it was certainly more deserved than Duan who got one simply for being Chinese, despite being 28 years old and ranked 99)? Wang not only used her birth privileges to get another MDWC into Beijing the following week, but to also get a performance bye into the second round. Is Wang more important than Sakkari, or should she be? She's just fortunate that her country is ploughing in all the money it currently is, and hosting all these very big events, just like the slam nations players are fortunate that their country hosts a slam.
Slams are obviously the most prestigious tournaments, but free entry into P5 and PMs and all the points and money that come with that can be just as lucrative. If you scrapped WCs altogether then it would be a far level playing field, not a rule for one, but not the other.